Vanilla Treo750

Download zip files from here

Extract zip files and find 2 cab files.
*1_CHEE_MountExtROM.CAB
*2_Chee_Extrom_rename.cab

Copy both files to Treo750

Install 1_CHEE_MountExtROM.CAB
Perform soft reset
* You should see the Extrom now

Install 2_Chee_Extrom_rename.cab
Perform soft reset again
* Extended_ROM now renamed to ExtendedROM

Two files contained in ExtendedROM
- carrierdb.pxp
- cappackage.pxp

Use File Explorer to browse to ExtendedROM\Partition
- If you want Vanilla: delete both files cappackage.pxp & carrierdb.pxp
- If you want to replace the current carrier settings with another: replace cappackage.pxp
- Only delete the cappackage.pxp if you want to keep the new carrierdb.pxp

Perform a hard reset: press the red off button together with pin reset