where is your cable junction at in your home?
If its in the basement, garage, utility closet, then its possible so long as you have an outlette, if not you can get a light socket adapter that will offer you an outlette.
Diplexers will come with directions but if not its like the exhuast on your car, 2 into 1 back out to 2.
The diplexer looks like a coax splitter, one side has a port labled In/Out, the other side has a port labeled Sat and the other one of the following, Ant/Cable, UHF/VHF.
You will need 2 diplexers, and 2 2way splitters, and 5 coax jumpers, 4 at 6 inches, 1 at 3 foot. The first diplexer will have the coax that ataches to your receivers sat feed line by way of the In/Out port, atach a 6 inch coax jumper from the Sat port to the sat port on the receiver, atach another 6 inch jumper from the tv output port on the receiver and then to the in port on one of the splitters, now atach a third 6 inch coax jumper from one of the out ports on the splitter and take it to the remaining port on the diplexer, put the 3 foot coax jumper on the remaining splitter port and run it to your tv.
Now the last diplexer will atach to the coax line that is going to your receivers location by way of the In/Out port, the coax line that is coming from the dish will connect to the Sat port, take your last 6 inch jumper and connect it to the remaining port on the diplexer and then connect it to the in port on your splitter and connect the two free cables at the junction to the splitter and your set, you will need to be sure that all tv's are set to channel 3. I cant garauntee how well your picture will be but this will work.