|more useful options|
First up, don't worry about the LIB and INCLUDE environment variables. They don't do anything for Strawberry Perl anyway.
1) Copy everything that's in the C:\strawberry\perl folder to C:\usr. Update: This doesn't mean that you simply copy that "perl" folder into C:\usr - that would result in the wrong directory structure for #!/usr/bin/perl to be pertinent. Instead you copy the folders that are in C:\strawberry\perl (namely bin, site and lib) into the C:\usr folder.
2) Rename C:\strawberry\perl to C:\strawberry\perl_hide so that it never gets loaded by mistake. You could delete it entirely if you're happy to burn your bridges.
3) In C:\usr\lib\Config.pm and C:\usr\lib\Config_heavy.pl change every occurrence of C:\strawberry\perl to C:\usr
4) Amend your path to include C:\usr\bin instead of C:\strawberry\perl\bin.
Afaik, that should be all you need do ... except that I don't how CPAN is affected. (I still install modules by the older, unautomated procedure, and don't use CPAN.)