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Hi Vince,
From the description of your post, I understand that you wish to Implement SiteCatalyst via DTM and you have multiple RSID to send data depending on the User's state (A or B). If my understanding is correct, here is what you need to do... Yipeeee 
Solution: Once you all sitecatalyst tool to DTM web property, you can configure the tool setting and define one or more RSIDs for Stage and Prod. However, does't let you put your custom code to dynamically decide your RSID depending on the user state. Instead of using the pre-defined field to enter the RSID, just set the RSID is the s_code manually, the algorithm could be something similar to the one given below:
1. Declare a variable and save the user-state using some custom Logic.
2. Read this custom variable and assign the appropriate RSID.
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Hope this helps!
Regards,
Harsh Kabra | Adobe Certified Expert: Digital Analytics® & SiteCatalyst Implementation & Reporting®