just add your vendorID to the themes you want in the .alx file..
Attached a .133 with all themes enabled for T-Mobile USA (vendor id 100)
Just rename to Blackberry.alx, pop into the C:\Program Files\Common Files\Research In Motion\Shared\Loader Files\8900-v4.6.1.133_P4.2.0.85 folder (backup your original), then run Loader.exe from
C:\Program Files\Common Files\Research In Motion\AppLoader