You need m10tools from Virtuous to decompile m10 files, and then resize them.
i tried to open rosie.apk with m10tools and it just said unzipping failed
this is what came out in the log
ZipTool: Error: Assets directory not created!
ZipTool: Are you sure the selected APK does contain m10-files?
ZipTool: Ending
Unzipping failed