You have some control by the use of part markers and chords. As far as what notes are played, no. The 'A' part markers usually are simpler while the 'B' are busier. The choice of chords makes a difference - a C7b9 will produce a different line than C. I've also noticed that using a chord over 2 bars produces a different line than the same chord placed every bar. Example: C ///|//// seems to produce an 8 beat line while C///|C/// produced two 4 beat lines. This is probably the case down to 2 beats as well.

R