If the other Premiere doesn't have MoCA, then you need a MoCA adapter for it. Then you either need to plug the XL4 into the router with Ethernet, or put a switch at the second location, and plug the router into that with Ethernet. Or if the router isn't near either, get another MoCA adapter for it.
My Place: Premiere XL4 Lifetime 3/26/13 XFinity
3 TiVo Mini's on MoCA
Formerly Win MCE 3TB Ceton4 XFinity
Parents: XFinity Motorola AnyRoom DVR
80 HR Series 2 Lifetime 4/11/04 DEAD as of 11/2010