Eventually, I installed otfm: it works.
Just to fix my previous post, I had to click install.oar, not install_sys_progs.oar.
One more question (not related to otfm): on the M92 I experience the same problem that I have on the C65 AG, i.e. accented letters in file names are wrongly displayed. For example, "città" is displayed as "cittÃ".
Is there a way to fix this?