Packager was not really designed to solve that problem, however there are two different ways you can go about it. If the database-level is the only place you specify a collation, you can change it in SQL Server Management Studio properties. However, since SQL 2000, you can specify collations individually for every column.
I suppose you could use SQL Packager to generate an upgrade package and that should do the job, but it could well change other aspects of the database that you don't want to change.
may be a better tool, as you can view the differences easily and get a script output that you can edit and apply only the collation changes.