First - I trust that when you say VERY expensive, you mean that the cost of the consultant is a significant factor higher than the cost of an employee, even accounting for training, benefits, etc. If this isn't information you know, it's worth figuring out about where the consultant's costs rank compared to various employee levels.
First, I'll never hire a consultant that wants to work in a vaccum unless I know that I can reap the benefit of seriously awesome productivity and my team will never need to know the same skill set.
Once and a while that's true... but I'll say it's rare.
The rest of the time, I look not only for awesome competence, but also a tendancy to speak up and be able to both discuss and teach technical issues. I want the consultant to be able to diplomatically raise issues based on their wider experience and I want them to be willing and able to teach the rest of the team what they know. If the consultant can't do this, I won't hire them, they aren't worth the extra money.
It'd be nice if any employee (consultant or permanent) got everything they need day 1. But it simply isn't true.
If this is the first time hiring a consultant, you'll want to plan in extra time to equipping them. Not only because every hour they spend struggling is an hour you pay (alot!) for, and you can't amortize it over time, since the contract will only be there 6 months. But, more importantly, there are security things to consider when hiring a contractor. Different companies have different concerns, but there are cases where you may NOT want the contractor to have access to certain key business areas employees do. This is more standard in bigger companies with more to loose and more contractors flowing through the system... but be prepared that temporary access rights aren't easy and you need a plan.
Be sure of it and clear on it up front. Also, make sure your TEAM is clear on it and ready to support it. Chances are, you have a set area you already know of, the things that need to be ironed out usually are:
- How does he get what needs from others?
- Who will work most closely with them, and are there processes for sharing knowledge in place? if not, let's find a way.
- What does "done" mean? Who checks that it's done?
Realize that a short time employee doesn't have the opportunity that long term people have of learning slowly. Most contractors are eager and ready to pound out work, but you need to have a clear plan and way for them to demonstrate they have met your needs. Being clearer is always better, and if you manage to improve clarity across the team for this type of work - so much the better.
In particular, consider not only the tasking of the contractor, but of those around him. If he's working on a peice so isolated from others that no one can help or learn from him, you have wasted a great deal of his potential value. But also, the personalities of those on the team come into play. I like to stick the expensive contractor near a peice of work done by my most inquistive and collaborative team members. I know that type of person will absorb a lot and be able to retransmit it to the rest of the team. Sticking the contractor near the "quiet guy" is a real risk.
NOTE: When I say "near", I mostly mean in terms of assignment - an area of the work, not a physical location. That said, physically putting the contractor in a cardboard box in a corner is no good. Integrating them as tightly as any team member into the day to day flow is essential, and making sure they are not even physically in a corner, or back alley is a good idea.
Be a bit aware in the first weeks that you may need to make fast adjustements - if the inquisitive guy is bugging the life out of the contractor, you may need to make changes... the goal here is to make sure your team is learning, so that can be a real art, not a science.
Team Expectation Setting
Get clear with the team that this guy is here to be a team member and a teacher. If they aren't checking in with him, asking questions, asking for input and offering their own ideas, then they are wasting a great opportunity. Contractors serve a special need - a lifetime contractor has worked in MANY more companies than the average employee, and so has a vast real world expertise on good and bad ways to implement best practices. A single best practice may look obvious, but how your company does it vs. another company can have a significant impact on the outcome. Tap that insight and help your team leap ahead.
This usually requires quite a few chats in both group meetings and one on ones... you may have a naturally collaborating team who tackles this with no problem... but I'll say in my years as a development manager, I had 1 team ever who was "naturally" good at this, and many others for whom having a contractor on staff was the reason we had to push to become better sharers.
Check In Early and Often
Given that you only have 6 months, realize that you may need more check ins, not less. If you make it a point to meet with the guy one on one once a week, you'll manage around 25 sit down conversations. That's pretty good. Do it every other week, and you have only 13 occasions to share knowledge. If you told me I had only 13 chances to get someone to be efficient in a new group, and if I failed I'd loose a lot of money - I'd opt for the weekly meetups.
I find a one on one with the lead/manager to be particularly key for contractors - some of my best have had really great insights that were sometimes quite cynical. So having the opportunity to hear the insight (and the cynicism) privately, was a great blessing. Every organization has it's weirdness, and contractors often pick up on it faster and more clearly. Having that insight is both very helpful, but also slightly disheartening because it can strike at the root of organizational culture.
Personally, I like hearing that critique in private, so I can decide how best to try to make change without the rest of the team thinking "why are we so messed up??"
Also, it lets the contractor tell you honestly how things are going and where the points of impedance are so you can go back through equipping, tasking and team expecations as need be.
And... worse comes to worst, if you really can't get the contractor to work out well, go back to step one on hiring - at least if you do the steps above, you can feel relatively comfortable with having given this your best effort.