|I think you posted this is in similar terms recently and the consensus was to use a homeplug solution...?|
This was the post in question?
Doing it wirelessly requires that "both" routers have the capacity to allow it.
If using either a homeplug solution (and there are some "modules" now that act as wifi extenders...), or an ethernet/cat-5 connection between the two routers is not a viable option then...
This link will give you whole list of possible approaches/solutions.