I've got a Mayflash myself... it's not that hard of work... most people just buy the Sanwa JLF and buttons, and put shit in themselves.
Moderately difficult:
Steel dremmeling -- dremmeling is pretty uncomfortable. It's like your first time driving a car. Keep that shit smooth, and you'll be done grinding those 28mm holes to 30mm in no time.
De-soldering -- get the braid on there, put the iron on for a few seconds, and lift both at the same time. Monotonous, boring work that's not too hard. Just don't go overboard and screw up your solder point. Use extra lead when soldering on connections for extra EZ mode.
Soldering on to PCB -- yeah, the points are small, and kinda annoying. Just make sure you follow a diagram and work diligently. Not too hard. NEVER 4GET: USE COLORED WIRES. THEY WRILL HERLP YOU ROTS.
Easy:
Snapping on buttons -- after you have your 30mm holes, insert, and secure them with snap-ins.
Installing a joystick -- okay, the stock stick is on there kinda tough. Just pull out your balls and twist that shit out. Then, screwing stuff in should be easy as hell.
If you don't have the tools, go around your neighborhood, go to your campus wood-shop, or just go to home depot or something to ask for help.