Comment #2 on issue 2888 by [email protected]: [musicxml2ly] beams and lost lyric syllables
http://code.google.com/p/lilypond/issues/detail?id=2888
With autobeaming off, beams are interpreted as melismata for associating lyrics with music. So it might be smarter for now to keep the autobeaming on, and just override any beam anyway.
In the mean time, file a feature request for some property breaking the beam/melismata connection even for autoBeam = #f. It sounds like it might be useful for more than just your use case.
