Heya -
I don't know if it CAN be done, but I have never succeeded.
I had a broody hen who refused to leave the nest, even when I took the eggs. I tried for three weeks or more, and finally, I just took pity on her and let her sit on some eggs.
She hatched out two of them - only one survived, and she is taking fantastic care of it. The only thing to get her off that nest was to let her have a chick that she hatched, and then she left the nest to take of it. The chick is 6 weeks old now, and she has just started laying again.
If you don't mind a few more chickens, I'd let her hatch some - it doesn't have to be a lot, just three or four will make her happy. She's not going to lay eggs while she is broody and sitting, anyway - so why not get some free (without working for them) chickens.
The nice thing about a hen brooding the chicks is that you don't need a brooder setup, or a heat lamp, etc... and it is just so darn cute to watch the mama hen take care of them.
Peace -
Meriah