Yes there are special canti bosses that thread through where the bottom threaded holes where the magura adapter now sits,justbackdated can get them as i think Sithlord inquired about a set for the RC35's i sold him,not sure of exact cost but somewhere around £28 iirc
Bill-If you have the tube bridge type RC35 with the Magura specific bridge, you will need to swop the whole bridge for the canti/v brake type together with the pivot studs and plates etc.