I'm having the problem as well. I've saw a related post that suggests using NaviagateURL with a concatenated query string, but this doesn't seem like the best way to do it. If I attempt to pass the control key to EditURL, I get the error mentioned above.
I tried looking at some of the core modules to see how they accomplish this, but couldn't find any that use multiple controls.
Any help will be greatly appreciated. Thanks in advance!