TwoLAME is an optimized MPEG Audio Layer 2 (MP2) encoder.
TwoLAME should be able to be used as a drop-in replacement for
LAME (a MPEG Layer 3 encoder). The frontend takes very similar
command line options to LAME, and the backend library has a very
similar API to LAME.

You'll need to have libsndfile (also available from SlackBuilds.org)
installed if you want to build the twolame frontend (which you'll
almost certainly want).  :)