I had started to write a python script for conversion, but the it came to my mind to check here also... My initial goal was to just fill in the layer names into the xml file.
But there might be more interesting things. Doing just a quick search, I …
Apparently your calibre layer map file looks different.
What is the structure you assume in the file?
Ours look like this:
2.20 blue @<somePath>/calibre/v1.1.6/bitmaps/blank.xbm RX_label 1 1
Regards
Johannes