I am sure that an easy (as in defining an alias or something) workaround exists (I use it, but don't have my empeg handy, and can't remember what it was exactly). I think this was discussed several times, so serach a bit...

Hm, I think that it boiled down to df working if given a single device (or was it mountpoint) as parameter, and those, in turn, can be gleaned from /etc/something-or-other. So, a bit of grepping etc would probable do...

Sorry for not being more helpful...