Tools for Loading .GSP Files

Hello everyone. I've been looking for posts about .gsp files, not so much for patching, but for creating cures or forcing them onto devices that have problems. I've worked with .gdc and .rgn files for many years, but I haven't seen any virtual tools for .gsp files. In one specific case, I have a device that I need to repair. I've already obtained the replacement .gsp file, but I haven't been able to transfer it to the device in its pre-boot mode using the Garmin updater, Cure 3, or GmapTool. Where can I find more information about .gsp files? Thank you very much.