Well, theoretically:
24 base (max from 4d6)
10 weapon
2 knost's
2 kyosho's
61 str (92 str)
16 PA
8 seeker
9 bard buffs
1 prayer
3 divine favor (paladin past life)
3 monk past life x3
*7
1001 points of damage.
Pretty **** unlikely though; not only do you need all the buffs and past life feats, but only 1 in 1296 hits would generate a 24 base damage, and only 2 in 19 of those would be on a 19 or 20, for a total chance of 1/12312 hit chance, with all the buffs.
I could be missing something that would make it slightly easier though.