http://www.slax.org/forum/viewtopic.php?p=79870#79870
I found that the slax 6 series won't load any .mo module at boottime, only lzm modules.
documented on: May 06, 2007, Dutch Kind
http://www.slax.org/forum/viewtopic.php?p=80202#80202
to convert mo to an lzm, use
mo2lzm