When I got tired of screwing around with SUP, I just unpacked all the
   appropriate tar files, faked a last.allsrc and when.allsrc file, and
   ran sup again to update those files that had changed.   Imagine my
   surprise in looking through the output of sup to discover that IT
   DELETED MY ENTIRE WORKING KERNEL SOURCE TREE!!!!!

I've done that myself, except that I was a bit more careful.  B-)  You
could run sup with `-f' to see what it thinks it should do, or leave
out the `delete' option the first time (but *only* until you've got
your initial tree set up).