relative datapath for MOVPY

Dear all,

I would like to use Matplotlib with movpy (Movable Python - Movable Python
is a Windows distribution of Python that doesn't need to be installed. It
easily fits onto a USB memory stick.

With the great help of the Movable Python author, I manage to install pylab
on the stick as well. It even runs with iphyton!

Unfortunately pylab writes all the fonts and stuff to the "home" dir of the
Windows PC. I tried to change the datapath in matplotlibrc, but I could not
manage to use a relative path. It crashed. A absolute path is no so good,
because USB Sticks can have different drive names on different Windows PCs.

Does somebody knows a solution to use a relative path for the datapath