It looks like Munzii resurrected an old thread and added his new question. This is generally not considered good form unless your question is identical to the old question.
Nonetheless, we're here. It's time to RTFM.
The RSLogix 5000 Help file has a good description of the CIP/DH+/CIP with Source ID options for Communication Method. To communicate through a 1756-DHRIO to a PLC-5 on DH+, you want the DH+ Communication Method.
When you are using the DH+ communication method, the CIP Path doesn't go all the way to the PLC-5 node on the DH+ network. Instead, the path only goes as far as the 1756-DHRIO slot. In your case, delete the last "3, 41".
The selections you make under "Communication Method" define the DHRIO and DH+ portions of the message function.
You will select Channel B, as you described previously.
You will enter 41 as the Destination Node. It is crucial that you enter this value in Octal notation.
Because you are going directly from the DHRIO to a DH+ node, you are running a Local DH+ message, as far as the DHRIO is concerned. Enter zeroes for the Source Link and the Destination Link.