Routing based on header record RECPOR in IDOC File

I am working a flat file (actually, its an IDOC file) that will enter the configuration scenario through a Seebruger SFTP adatper. Since this is a flat file, and not XML, I need to convert this to XML prior to doing content based routing in the receiver/interface determination.

I am most concerned with the RECPOR field.

RCVPOR : Receiver port

internal data type : CHAR

Internal length : 000010 characters

Position in segment : 024, Offset : 0263. external length : 000010

The scneario is a simple passthrough. What I envision doing is converting the IDOC Flat file to an XML structure, then doing content based routing on the one field I am interested in, as mentioned above.

Is there a way to do this without modifying the payload in teh sender/receiver channels, or am I going to be forced to doing content conversion with MessageTransformationBean?

Since all of my routing will be done on 10 characters, I see breaking the file up into 3 fields...characters 1-263, 263-273, 273-EOF does some one have a sample of how to separate this, and how to recombine the values in the receiver?