[plt-scheme] Make multiple attempts to open DrScheme join running process?

As I've mentioned before, I'm running DrScheme in a thin terminal lab
and have 30 students sharing one server. Students seem to be in the very
bad habit of double-clicking files to open them, not realizing that (I
think) this spawns a new DrScheme process and eats up lots of memory.

Is there any way to have subsequent calls to DrScheme (well, the
drscheme binary) check for a running version for the given user and open
a new tab with the file if there is one, or open a new instance if not.

A pointer to a command-line option or a manual entry to check is
sufficient, if there is one I didn't see in my cursory check.

Thanks,
Todd