Building a "safe" python?

[martin.nordstrom87 at gmail.com]

I'm making a game where you'll be able to make your own mods and I
want to be able to write these mods in python. However, python has a
lot of "dangerous" functions (like erase any file on the harddrive
etc) so I want a "safe" python. I first found RExec but that is
disabled in python 2.5 so I was thinking about building python from
source with a few changes.
The changes I was thinking about was to change the import function so
that it should only be able to import the .pyd-files that I allow (and
it should of course still be able to import any .py-file) and remove
or change the builtin functions that are "dangerous".
Is this enough to make a "safe" python that can't do anything
"dangerous"?

I'm going to embed this "safe" python into my game and I've discovered
that when I embed the original python and the mod wants to import
a .py-file that is not in the game directory it will search for
the .py-file in the python directory that is installed on my computer.
Can I somehow prevent the embedded python to look in the python
directory?

Thanks!
Martin