I put custom firmware on my fat PS3 last night, everything is running seamlessly until my friend connected it to the internet. Not for PSN, because I never have and never will you PSN honestly (not much of an online gamer).
But anyway, he was playing Little Big Planet before he connected it, a back-up version to test it out using the fallout 3 disc. And after he hooked it up to the internet Little Big Planet wants to do a software update to 1.30. What do I do?
It's just a game update, not a system update. You can play LBP without it, but if you (or your friend wished) to play online you would need a PSN account and latest game update.
But you should also update as patches almost always contain bug fixes. Games often have glitches or bugs that could prevent you from playing or saving as you should be able to, so patches are crucial in those cases. I think updating your game via patches is safe using kmeaw, unless your game's eboot.bin has been pre-patched before. But since most games (99%) play with their untouched eboot.bin files, updating them should not change how they work on kmeaw. In any case, you should keep a backup of your game on a separate hard drive, just in case.