I did this in so deviant way - using third-party RPMs. /usr/lib/libfm/modules seem to be not presented in slitaz. copying it from
rpm2cpio libfm-1.2.0-1-rosa2012.1.i586.rpm | cpio -vid
also link needed
ln -s libmenu-cache.so.1.0.0 libmenu-cache.so.3
menuitem Tools -> Find Files... now works
I wrote about problem in cooker.cgi?pkg=libfm before
http://forum.slitaz.org/topic/pcmanfm-mount-devices-as-user/page/2#post-29772