Is there a device that lets you connect to a computer using dsl from a phone jack in another room without wires?

What is this 'device' you are referring to? Are you using your phone lines in your house to run a network? If so, then no, it will be almost impossible to run a DSL modem to that network.

The reason is, a phone line network, which typically runs at 1mb per second, uses 'token ring' methology... basically one computer holds the 'token' and the other computers are constantly asking for it, and it travels ONE direction, not 2 way communication.

For the price, I would install network cards in all your computers, and run CAT5 cable, with a router near your DSL Modem. that way, the DSL modem will see one computer, but all the computers, attached to the router via CAT5 cable, will be able to access the internet.