Depends on what your using and what your trying to do...
Start, Back, Guide, common ground, and the face buttons are easy as pie. You'll need to take off part of the trigger assembly to get to the signal for LB (I forgot either LB or RB, pretty sure it's LB...) RB is easy as well. The Triggers, Sync button, and Dpad ones are a pain in the ass though...
Dpad inputs are very fickle, so hot glue them right after you've confirmed the input is correct and working, or they'll disconnect. Sync button is a really tiny connection and can be rough geting the wire to connect to just the signal and nothing else (you have to take off the original button node thing to see it) And the triggers aren't really hard but it's a PITA to get them COMPLETELY off. Then you wire a resistor between two points and a signal from another... no connecting to the common ground for those guys though as the triggers have their own ground.
As far as burning it IDK... I've never left the iron on it so long that it actually messed up the board.. and I've left it connected for quite awhile... I have skrewed up a wireless board though because I pulled too soon removing one of the triggers and it ended up ripping off a contact...
BTW if you are even going to MESS with the triggers know that unless you plan to put a resistor between the bottom two holes (there are 3 once you remove them) the PCB WILL NOT WORK. The board "freaks out" if there isn't something conntecting the two lower holes together.
