I have an idea... take a picture of the clown, then a picture of the anemone. Then superimpose the clown onto the anemone with a photo program, print it out and tape it to the side of the tank... maybe that'll help give the clown the right idea.
Otherwise, like Doug said, it's totally up to the clown now. When I added my BTA I had to remove the pink tree coral they had been hosting in to encourage them to move... when it was still in the tank they had no interest in the anemones (they're ORA clowns)... now they hardly leave them.
HTH