I've been fiddling about in the moc config & keymap files. I've actually got it working how I want it to.
I have fast_dir1 & fast_dir2 assigned to ! (Shift 1) and " (Shift 2) respectively and I have the volume_10 through to volume_90 assigned to F1-9 (I've commented out the exec_command to use the F keys).
However, try as I might I can not get the M (Alt) key to work, neither can I get the £ (Shift 3) key to work for fast_dir3. In fact, if I included the £ sign in the keymap file, mocp wouldn't start.
This is really not a problem, but I'm puzzled as to why I couldn't get them to work.
I use a Dell Latitude D520 correctly mapped to the UK Dell Latitude keyboard.
Anyone have any ideas?