Thanks for the TX1 1.00g firmware dump, Microfunguy... revision 402 should now support both TX1 versions. Looking at other cameras, I engineered some code which should allow a readout of the orientation sensor... given that it's actually in the device (and can be read out through the functions I made).
PhyrePhoX: seems like you've got the two wrong cameras
A620 doesn't have IS and S3IS has a completely different code layout for the IS functions, so no orientation sensor stuff with those yet. Maybe later on but it probably requires a significant amount of RE.
Anyway, I'll make a note to start searching for the orientation sensor in other places since it should also be present in non-IS cameras. The 'IS' function is probably a wrapper for the generic sensor and the IS subsystem probably just happens to use it for something, hence the function.