Installing The Asp.net Application Services In A Custom SQL Express Database.

I know that by default asp.net 2.0
creates the aspnetdb sql express database for storing membership, role
management, profiling etc. And I saw we have the aspnet_regsql tool to
have this installed in a standard sql server. But what should I do to
have these stored procedures, tables etc installed in an existing sql
express database? Aspnet_regsql doesn't seem suited for that.

I've noticed some sql scripts in the framework folder like
InstallCommon.sql, InstallMembership.sql, etc. They seem to be used to
create the regular aspnetdb.mdf database, should I just modify those
and run them against my own sql express database or is there a tool or
an easier way?

Cheers,
Frank.