Dee could you try discipling her in whatever way you usually do? e.g. I do time out with my daughter... when she starts to get too bossy, warn her that that's not a nice way to play and that if she keeps yelling she'll have to have some time out to calm down.

I always try to follow through on any warnings, and it seems to work. The other thing that works for me is taking away favourite toys for a length of time.

It's not so much the bossiness etc that's a problem for me, it's the disobedience after receiving a request to stop.