[plt-scheme] installing a .plt file off $HOME

Hi,

I'd like to install SchemeUnit on a machine at school where I don't 
have write access to the installation directory.  Is there a way to 
install a .plt file off my home directory?

I've tried (run-single-installer <filename> current-directory) in 
plt-single-installer.ss and running setup-plt <filename>, but the 
destination directory is always the default collects/ directory.  I've 
also tried setting $PLTCOLLECTS to the directory to which I'd like to 
install. 

- ethan.aubin at pobox.com