So I needed a nice way of updating bits of Armalyte, without some of the source data, a lot of it was stored directly as binary anyway while we were writing it...And building the necessary data back up and loading it properly is proving troublesome and a bit slow.
After a bit of experimentation the quickest way I've found is to patch a Vice snapshot.
Use Tass to output a scatter link file, 2 bytes for length 2 bytes for memory offset followed by the block assembler (Dasm has a similar output format)
The scatter link file
The output filename
The new program counter
And it'll go through patching your new code into the snapshot, then saves out a new one
If it sounds useful drop me a PM and I'll email the exe and source.