[meanfishy]

Ok, we need to establish what a .CAB is first;
CAB files are also often attached to self-extracting programs where executable program extracts attached CAB file. Also CAB files sometimes embedded into other files, for example MSI files are usually contain one or more CAB files embedded. You can easily recognize Microsoft CAB files since all CAB files have specific marker at begin of file, identifying file format. For Microsoft CAB files this marker is a four-letter tag MSCF at start of CAB file.

you install what you want to use directly to the phone without having to flash, or cook a ROM and if you don't like it you can delete the cab and you don't have to re-cook your ROM in order to get rid of what you added. what are you wanting to added and that will help narrow down what you need to do