Same process as gone over earlier in this thread. Same thread at XDA has the cab links direct from MS in it near the end. There were 2 updates and 2 language packs each for an intermediate (8112 I think) update and then 8773. Used the upload batch tool. All I did was swap in the new files, dragged the old 7740/8107 update files out for safe keeping, and then ran it on my old test phone, and then my current one.
So far no problems, made a test call, text message, wifi browsing working etc...
pictar