Have a safe ride brother!!
The parts above are for the 6B connector (socket) and not the 6A connector (pin). If 6A is required on the SESG2 then the part numbers will be different. According to the service manual for my SESG2, the symbol for connectors is as follows:
-< denotes socket connector
<- denotes pin connector
So in order to create the 6A connector it will be the corresponding connector type to 6B but it will need to be the pin version. However, I don't see that simply supplying power and ground will solve the issue. If you note the diagrams below, the 6A connector comes from the "vehicle audio harness" and 6B comes from the "vehicle interconnect harness". In order for additional accessories (XM, NIM, etc) the CAN + and CAN - signals must be present for the head unit to know that the accessories are there. These signals (as you referenced) are present in both the XM and the NIM diagrams for connector 6B. However, in the SESG2 service manual it shows no connections tied to 6B for CAN (+) and CAN (-). So ... I don't see that additional connectors are needed. The only additional connections required are as follows (all connectors are referenced to SESG2 service manual):
1. Cut the Yel/Orange wire running between connector 28B (position 13) and connector 274B-1 (position 6).
2. Take the YEL/Orange wire on the 28B side to connector 6A on the SESG2, terminate with required pin, and insert into position 4 of connector 6A
3. Install a new Yel/Orange wire terminated with required socket (p/n ref below), insert into position 4 of 6B and run that to the open Yel/Orange wire on connector 274B-1 (already inserted into position 6)
4. Cut the Yel/Violet wire running between connector 28B (position 13) and connector 274B-1 (position 7).
5. Take the YEL/Violet wire on the 28B side to connector 6A on the SESG2, terminate with required pin, and insert into position 5 of connector 6A
6. Install a new Yel/Violet wire terminated with required socket (p/n ref below), insert into position 5 of 6B and run that to the open Yel/Violet wire on connector 274B-1 (already inserted into position 7)
As Carl pointed out above, "Supplying the Violet/Gray wire and the Blue/Yellow wire to slots 2 and 15, respectively, of connector 27A will "probably" allow use of the CB accessory in conjuction with the non-Ultra overlay harness, p/n 70169-06. According to the non-CVO wiring diagram, slot 2 is for the PTT/mic, and 15 is for "DSCAR switch matrix in (?)". These would need to go to connector 6A position 1 (Violet/Grey) and 6A position 2 (Blue/Yellow) so that they could also be carried through on the 6A/6B path.
All future accessories will now carry a fully functioning 6A/6B path. In the case of the SESG2, the required CAN signals are not carried or supplied via the 6A and 6B connections - they are carried directly to the iPod interface module via connector 274B-1 and 274A-1, These signals need to be present on connector 6A (pin type) for each subsequent accessory module installed. The new accessory will then carry all signals trough on 6B (socket). Reference the NIM install intructions showing all signals carried through on the 6A/6B path. Remember, for each new accessory, the existing 6A/6B connection is de-coupled, and the new accessory is is inserted into the chain. I've attached page 4 of the NIM install showing the 6A/6B path. For reference, we'll call the 6A connector on the right the start of the chain (existing 6A on SESG2). So 6A on SESG2 carries new CAN+ and CAN- signals into 6B of NIM, then 6A of NIM provides CAN+ and CAN- to new wires of 6B on SESG2, which then in turn supplies CAN signals to iPod module via connector 274B-1. Don't let the connections going to 28B confuse you, only look at the signals provided via 6A/6B.
This is one way to skin a cat ... hope this helps.