Hi Michael,
By coincidence I've been looking at this myself today.
My seat airbags have been disabled through VCDS as above - adaption for channels 3 & 4 set to 1.
I don't have a MIL or any other warnings apart from when scanning the airbag module (15) and this just says that the 2 airbags are disabled.
I'm looking to get a couple of resistors like you've found above, and installing them and re-enabling my airbags through VCDS. This will get rid of the messages when I scan the airbag module (hopefully)..
Hope this helps...
Oh - I've got an 07 RS4 not S3 but should be similar...
Thanks
Mike