Preserve ISA & GS Envelope Header

Hello,

I am new to BizTalk server and was looking for a little help or insight that could put me on the correct path.

Currently we are using a fairly old Translator package by EDS called EDI*ASSET, but we have been encountering quite a few issues with it lately due to limitations in the software.  I am looking into the posibility of moving to BizTalk 2006 R2 as a replacement, but have encountered a few difficulties.

In order to transition smoothly I would prefer to not change anything in our Host system, so I have been attempting to use BizTalk to create the necessary document Maps to emulate how the system currently works.  The issue I am having is with the ISA and GS envelope nodes.  All of the X12 schemas appear to start at the ST level, with the ISA and GS created by BizTalk. I will require the ability to have these nodes present on both my inbound and outbound documents, as they are created and tracked by my host system.

Essentially I have to be able to take a flat file document such as the following 997

997 HEADER00          00          ZZ12345678       ZZ87654321       0809111045U00200+000006380P> FA12345678    87654321    0706140953+00000278X 004010      9971000
AK11PO1+000100150
AK2185010250
AK51A0   0   0   0   0
AK91A1+0000011+0000011+0000010   0   0   0   0

and turn it into an X12 file like the following and vice versa:

ISA*00*          *00*          *ZZ*12345678       *ZZ*87654321       *080911*1045*U*00200*000000638*0*P*`
GS*FA*12345678*87654321*20070614*0953*278*X*004010
ST*997*1000
AK1*PO*100150
AK2*850*0250
AK5*A
AK9*A*1*1*1
SE*6*1000
GE*1*278
IEA*1*000000638

The Document map seems simple enought, but is it possible to preserve the ISA and GS headers or can these values only be set by the Pipeline?

Any help on this would be most appreciated

Thanks,

Adam