Invoke ItemCommand from a custom toolbar button

[Martin]

(Please ignore this post, since I have created a support ticket in the mean time. I will update this post, when I get a solution).

I have added a custom button to the FileExplorer toolbar (according to this help page). How can I invoke the server-side ItemCommand of the FileExplorer control when this button is clicked?

What I'd like to achieve in the end, is to load the currently selected file into a RadEditor control on the same page.

Thanks.

-Martin