As a side note, I have smacked myself and yelled: RTFM, or at least, RTFFYI. Anyhow, if anyone else gets stuck doing this, I've figured out that you can specify SQL statements to be run upon valid connection. Therefore, modifying my orace-ds.xml by looking at the WIKI where it states:
<new-connection-sql> - an sql statement that is executed against each new connection. This can be used to set the connection schema, etc.
I've added a line to my oracle-dx.xml that looks like:
<new-connection-sql>ALTER SESSION SET current_schema=DB_ANOTHERUSER</new-connection-sql>
I will not say this is the most elegant way nor it is the proper way, but it does work for me :-D Anyhow, maybe it will help someone down the road!