I assume you're talking about the square one and not the rotary sytle. It's pretty easy. Hook it up and go. You may need some funky fittings and what not, but they're around. Check
http://www.kilbyenterprises.com/ for the connections to the compressor. They have everything you need and I've had great service from them, but, they are pricy. Easier and cheaper to get the common fitting from a hardware store. In terms of modifications, if you mount it straight up and down you should be ok. If it leaks oil you can plug some of the internals, but you may not need to. Some seem to leak while others don't. Make sure and check the oil. It'll burn up pretty quick if it's empty.
Good luck.