You can get camera specific L-Brackets but theyre not cheap. Really Right Stuff ones seem to be popular (
http://reallyrightstuff.com/Items.aspx?code=LPLATES&key=cat) and I think you can get them from WEX.
Alternatively, Manfrotto do the 341 Junior Elbow, which is much cheaper and does the same job but wont fit your camera so well. This isnt my setup but its pretty much as I use mine -
http://www.flickr.com/photos/victormk1/4853822407/
I've put a manfrotto 323 plate between the 341 bracket and the camera so that the bracket doesnt need to stay on the camera all the time. The bracket connects to the 454 macro rail with another 323 plate but you could connect it to whatever head you have.