Setting up large scale virtual hosting

Point me to the right group if this is the wrong place to ask.

I've got a year to design and build an online course in
elementary programming, to a 2-year (tribal school) college audience.
I want use php or perhaps ruby/rails, and gradually work towards
teaching how to generate html from code according to runtime conditions.

They will all need individual file system spaces and website spaces.
I'd rather *not* set them up in ~username/public_html spaces, because
that complicates file path issues when writing code.

I know how to setup apache2 for virtual hosting, but what I really want
is what shared host services offer: /pathtohome/username/ file system
accounts that include a symbolic link to a virtual DOCUMENT_ROOT they
can write to.

How and where do I learn how to set that up?

Davide Bianchi wrote:

> Actually, it teaches them how to code their stuff so it's independant
> from *where* is actually installed (relative path as opposed as
> absolute ones).

Being smart about relative paths is assumed. I had something else in
mind. In the php context (if any of the students ever get that far)
you (I) often need to translate back and forth between file paths and
urls. Php's $_SERVER['DOCUMENT_ROOT'] becomes useless in the
~username/public_html context.

......make a simple, semi-automatic image gallery by reading a directory:

$url = some_php_str_replace_func($_SERVER['DOCUMENT_ROOT'],"",$path);

That sort of thing gets ugly in ~home accounts, especially if you want
to write code that would also work under a real document_root.