If you are really worried about removing parts, then masking tape everything that shouldn't be painted.
As Matt [Kunama] said, "Everything that can be unbolted needs to be separated. Mirrors, focuser, screws, bolts etc...."
In this case, rather than remove, you'll have to mask all that stuff. Really fiddly work.
Make sure nothing can drip or spatter onto the optical surfaces.
This web page tells you all the steps :
http://www.dulux.co.nz/advice/how-to...-surfaces.html
The really shiny finish comes from applying 2-3 clear gloss coats over the paint coats. But I've never tried this. A paint store can probably advise if a clear brush on polyurethane gloss can go over and bond to a gloss enamel. I've only ever used them on stained or raw wood.
Where do you live? If you strip the tube, and several of us are telling you that you should, I'm sure there is an IIS member in your area who would be willing to step in and help reassemble if you really get stuck?
The most important thing is, if you spray, you must strip the tube or you'll wreck the mirrors, if you brush, you might get away with it but you have to work very very carefully and mask everything.
Joe