REDCap Gateway

We've received a request to set up a Gateway on our On-Premise Gateway server to a REDCap data source.  Is it supported as a gateway?  What data connector is used in the definition?  What else is involved or to be considered?  I've seen post on connecting the desktop to REDCap which involves a token or key, where does that piece go in the definition, is it stored on the physical gateway server?  

Thanx in advance

patw