Perusing this book, I came on a pretty good build for a sneak-attacker.
There is a new arcane 1st level spell that is a swift action to cast and allows you to sneak attack constructs for one round. By the same token, there is a new cleric 1st level spell that is a swift action to cast and allows you to sneak attack undead for one round.
So cleric1/sorceror1/rogue3/invisible blade 5. Sneak attack almost at will, and almost anything.
Because you're a cleric, you also pick two domains (Farlanghn is nice, for good fortune and freedom of movement 1 round per day), and you can use your turn undead attempts with a feat such as Divine Vigor. If you want more uses of sneak attacks versus undead, pick a level of Favored Soul instead of cleric. Actually, can you take a single level of cleric AND a single level of Favored Soul, for a pletora of first level divine spells ? If yes, even better !
With that, focus on feats that boost you sneak attacks (from BoED, PsiHB, and CAdv), which would make your sneak attacks do xd8 versus evil critters, reroll 1's, and if target fails an almost impossible to succeed fort save, is staggered for one round.
Boom baby.