Extend LAN with Coax?

Let me know if it is possible to do this:

DSL router in room 1 connected via cat5 to CCK, which is connected to coax to LNB, with other coax port to a client of Genie. Coax goes to Room 2, which connects coax to Genie DVR.

I have an old deca broadband adapter from a prior install not being used. Is there a way to used this (or some other device) at the room 2 location to connect a PC to the LAN using the DTV COax network to get back to the DSL router?

I am using powerline networking to connect this PC currently, but it is very slow and if I can use the coax somehow to ride it back to Room 1, that would be great.

Thanks
Marc