Yeah right, I use that too.
I made a list of quests that require murder. Every faction has at least one (even the cult) but they should be quite easily to manage so that at least two or more factions should be playable for a pacifism char. I think such one wouldn't join the fighter's guild or Morag Tong like a pacifist would not join the army
Okay here we go:
Hlaalu: 4 of 31 (1 optional that you can talk out so it's: 3)
Redoran: 5 of 36
Telvanni: 9 of 29
Fighter: 21 of 31 (2 optional: 19)
Thief: 2 of 30 (1 is same as Morag Tong)
Mage: 4 of 31 (2 optional: 2)
Cult: 1 of 25
Temple: 3 of 24
Legion: 6 of 19
Morag Tong: well... 21 of 24
MQ: 5 of 20 (but only 3 are humans)
The game already gives you opportunities to talk you out and stay "good" so it would not even break the immersion (at least not for me).
I would welcome a mod like that and if not as big as ROHT or To serve Sithis I would try to translate it for the German Comm.