Attaching curtain poles to an RSJ

[RoyG]

We had French doors installed in a wall with an RSJ lintel above. The wall has been plasterboarded and skimmed and painted and now we're thinking of hanging curtains on 30mm poles. I'm wondering how best to attach the poles. It seems unlikely that the plasterboard alone could take the weight. How hard is it to drill through into the RSJ and what sort of screw should I use?
Would I be better off fixing a batten the full width of the doors?

[welsh brickie]

you can use redidrive metal anchors that screw into the plasterboard,I have used them to hang radiators to the wall in the past.Google :screwfix direct for more information on the fixings