You don't have to cmod all the files to 777,
On RC3 and 4 it replaced these files:
Keygen is replacing the files with new data...
/ - done!
/admincp/ - done!
/archive/ - done!
/clientscript/ - done!
/cpstyles/vBulletin_2_Default/ - done!
/cpstyles/vBulletin_3_Default/ - done!
/cpstyles/vBulletin_3_Frontend/ - done!
/cpstyles/vBulletin_3_Manual/ - done!
/cpstyles/vBulletin_3_Silver/ - done!
/includes/ - done!
/includes/cron/ - done!
/includes/paymentapi/ - done!
/install/ - done!
/modcp/ - done!
Thats about it