how to hang telescopic net curtain rods?

I would like to know how to support telescopic net curtain rods on a UPVC window without drilling into the frame. Have tried plastic self adhesive hooks, also plastic hooks with 'no more nails' adhesive, but both of these come straight off when I hang the curtain onto them. The actual pole stays up fine, but bows in the middle and needs a bit of help, anybody got the answer!