integrating WEBDAV and LDAP apache modules

Hello,

I'm trying to integrate WEBDAV with LDAP, but am having some problems. Here is the scenario:

A user has a certificate (stored on their hard-drive) they then login through a secure browser (i.e. https) to the apache server.
The apache server (using the LDAP module) validates the user via an LDAP server.

Once the certificate is authenticated, the user then needs to be able to use the apache WEBDAV module, in order to map drives to their PC and ftp e.t.c. (i.e. do the things that WEBDAV offers).

The problem is there is a gap between the LDAP and WEBDAV modules, i.e. I need to effectively be able to map user certificates to WEBDAV, so that I can check that the user who's doing the mapping is authenticated.

Does anyone know how to do this please without having to introduce a seperate database or something? i.e. Is there anything in apache that allows these 2 modules to integrate seamlessly?

Many many thanks if you can asssist.

Regards,

Jason