Eventhough feasible, I wonder what the expert will write / say.
There are a few posts on doing the work the other way around (which looks to me the sensible way to do things).
- Converting XML to JSON @ ThomasFrank.se
- Converting XML to JSON @ XML.com
To convert JSON to XML through XSLT looks to me a cumbersome approach as XSL deals with XML-valid files, not with text file