Hi,
I need some more information about receive loaction how you get the message (xml file) and where you received the file is it at (folder/ ftp folder / in url) ? and where to send….
if it is (folder / ftp folder)…it is very simple …create two XSD, one for input message one for Out put message the use mapping to align to XSD(u can use external XSLT which you have)..
if it is (in url)..no need use Biztalk server …user XML serilization using xml parser to fullfill you requirement.
suman kalyan betal