Mod_rewrite, Vhosts, And Errorlog

I tried searching the forums a bit and the Apache manual, but I was unable to find much related to my specific problem.

We have a system such that each user has a 'www' folder in their home directory so that example.com/~user will point to that folder. The user information, however, is not on the www server and instead we use a network file system to access the files in the home folder.

This all works fine and dandy with mod_rewrite. However, we want to allow each user to have access to the error logs, etc. for their own site. The best way to do this seems to simply store it in their home directory.

The problem is that how do you split these files apart. While it would be possible to have a separate process do it, the best way seems to just have each user be their own vhost. mod_vhost_alias seems to be applicable in this situation.

However, mod_vhost_alias relies on either the Host: field or the ip to split queries into their respective vhosts. As said before, our system uses the directory.

So the question is, is there a way to either use mod_rewrite to tell mod_vhost_alias what the vhost's name is. Or, is there a way to split the logs another way.