There is a house with internet access, and there is a workshop/guesthouse which has a phone line connecting to the house. The phone line is a copper wire pair, nothing fancy. The challange is to provide internet access through this wire. No rewiring, no wifi, just this line. 

There are extenders that can do this, but they cost several hundred $. These are based on dsl technology, so my idea is, that I put two dsl modems (I have two [d-link dsl-360r](http://4.bp.blogspot.com/_PXHgaDiK_nI/TGuXINVIgSI/AAAAAAAACDU/w5SQMtuUuNU/s1600/dlink-dsl-360R.jpg)) on both ends of the wire. Connect one to the router in the house, and the other to another router in the guest house. The distance is a below 100 meters. Both routers run dd-wrt. 
Will this setup work? If so, what additional step I need to take, other than described above? If not working, why?