Not to be a pessimist, but the bad thing about drum sequencers is they play to a strict tempo. The tempo of a song should be pre-determined. So if you didn't record the other music to a metronome, then a drum sequence will always be off. If you didn't do that, record the guitar parts to a metronome, make note of the tempo, then apply the same tempo to the drum sequence. Then it should be very easy to figure out a drum part and the part will be in time with the music.