the same way as you undercoat the rest of the mini! if you are gluing it on after painting, just make sure you clear the paint form the joint otherwise it\'ll weaken it
What I\'ve also started to do in such situations is to put some type of plastic bag -- a sandwich bag or other food storage bag, or a grocery bag or similar shopping bag -- over the hand with which I\'m holding the mini being sprayed (whether undercoating or varnishing). That lets me hold it much closer to my hand (or sometimes even in my hand, depending on what it\'s mounted to) and still spray without worrying about spraying all over myself.
recently, my mum was in hospital, and when i visited her i \'borrowed\' loads of the operating gloves! and they work a treat!
watch out though, sometimes the paint starts to \'eat\' the latex of some makes.