Documentation for the stand-alone SMT tracker can be found here here. The cvs package l3fSMTtracking.
HTrack is a specialised high pt track finder for tracks with a pt greater than 5 GeV/c. It basically works by finding straight tracks and constraining them to come from the primary vertex. Hence this tracker is not suitable for tracks originating from secondary vertices (although it should still find them with a lower efficiency). The vertex constraint helps in improving the pt resolution. The relevant cvs packages are htrk and l3ftrack_htrk.