X12 transaction (ST) in UCS Envelope and group

One of our partner is sending X12 transaction (X12 4060 350) in a UCS Envelope and group. Sample data below. WM fails to identify the transaction set. It does identify the UCS envelope and UCS header. How can we make WM recognize the transaction set as well? Any ideas?

ISA00 00 ZZAAA-AAA 02BBBB 1311181300*~004060027341100P*:^GSAUAAA-AAAAAAA2013111813002734110X004060USCBP^ST3502734110^M10AAAAJ8993223905131317Z13322105608645^P43004201311181255^V9AAD20131118125950^SE52734110^GE12734110^IEA1*002734110^

On another note, is it possible to add an EDI transaction set that does not come out of the box? So say if you have a transaction X12 5040 999 (hypothetically speaking) and you want to add this to TN. I can define the schema, but how can we make the EDI recognizer recognize this?