How can I add my pronouns to my email signature without leading people to think I am transgender or supportive of transgender?
In life, people make assumptions and jump to conclusions (valid or not) all the time.
You can do X thing, or say X thing, and your meaning or intentions may be X... but that doesn't guarantee that everyone will understand that you meant X, or that your intention was X: some may grasp that you actually said X, others may assume or jump to conclusions that you meant Y, or Z, or Omega...
In other words, you can include your pronouns on your signature if you want, but you can't prevent some people from jumping to conclusions or assuming things of your nature or identity.
Now, about the actual way of including it, I think it's fine just to put it along your signature and phrase it in a standard way, like this perhaps:
Pronouns: [your pronouns here]
Now, you've still haven't made clear why you want to do this, but in the meantime I will assume (oh, the irony) that you want to do it because your gender-neutral name leads to some people using the wrong pronouns when writing to you.
If that's the case, as suggested in comments, you could also use "Mr." or "Mrs."/"Ms." along your name and last name to smoothly point readers of your emails to the right way of addressing you.