Dependency trouble after installing backport

["Ron Rademaker" <r.rademaker@virtualbuilding.nl>]

Hello,

I've installed a backport of exim4 for woody (because I want to use xasm
and xasm needs exim 4), however this has caused some trouble. Namely
pretty much any package that depends on exim (like mailscanner) thinks
something is wrong and wants to completely remove my exim4 installation
and reinstall exim. I want to know if it's possible to make apt think
that exim4 provides exim so that everything will be back the way I want
it. (Add | exim4 to every depend line in the control files before making
the .deb and installing it would be a bad solution I guess).
Unfortunately I don't know where to find the backport source files.

Thank,
Ron