I used to hack my own Sims objects but never bothered to with the Sims 2. Now I've been bitten by the bug again and am using SimPe to get the job done. I've only done one thing so far: modded a painting to give me options to max all the motives (individually). I'll do the same with skill levels using a bookcase. I still haven't figured out the right way to adjust influence points though.
I'm wading through the Samurai Champloo series (currently on ep 4 right now) and am enjoying it muchly.