Yes it is possible.
BUT.
The message your receive is not the xml message. You will receive an application/www-form-urlencoded message which is basically a flat file of name/value pairs.
I have a generic project with schemas, maps and pipelines that will convert application/www-form-urlencoded messages into Xml, if you would like a copy email me.
You could also create a custom pipeline component to decode/disassemble this message