> Hmm... on *nix, things like this are not necessarily global, but per
> user.
> You normally install things in /usr/local or  a subdirectory of that,
> pretty instantly allowing each user to have a custom setup from there
> or from their shell login script. I know that Windows (not 95 or 98)
> has some unix-like features here and there, but I don't know how much
> in the users/accounts area.

Yep, I'm a pretty experienced Linux/BSD user - but my options are
pretty much limited to Windows or Mac, since I use a hefty array of
Adobe products in my work too.  I'm looking to buy myself a Mac in the
next few weeks, but for now I'm unfortunately stuck with Windows - and
Cygwin is as close to sanity as I can get here ;-)

> Cygwin is a *nix-like environment so I thought it might be possible
> from there...

It may be possible by setting the PREFIX variable on compilation, but
again as you say things make assumptions, so I still can't guarantee
the safety of my current Ruby installation.

I guess I'll keep playing until I find something that works for me, thanks :-)