hmmm...i like satriani's idea...itll get your hands relaxed great and fast:)

i dont know about warming up for 2 hours tho...theres a big chance of hurting your hands or simply getting too tired after a while during the show...unless there is a solo that you want to get perfect...all i do is go thro all my scales/exercises stretch your hands and now imma try puttin my hands in warm water:)