Is it possible to pass a path to an odbc entry that is in a merge module?

My merge module has an odbc entry.

My main installation asks the user for the path for the odbc entry
(indirectly - actually it asks for the path for the merge module to get
installed to)

I know how to make the merge module get installed to the correct path using
a directory identifier - but how do I tell the odbc entry within the merge
module the new path that the user selected?

I don't THINK I can use INSTALLDIR for this, because that path needs to be
set to where the main app is getting installed, most likely different then
where the merge module is getting installed.