UPDATE: BAH! I was sort of wrong about this. Turns out, as noted in comments, that if you use the solution I outline, then when you hit the key combo, it re-enables the "Track Active Item in Solution Explorer" option that you want disabled. So if you do this, you need to hit the key TWICE - once to select the current item, once to turn the setting back off. If I find a better solution to the problem I'll update this post.
When I'm working in Visual Studio, I generally turn off the option to automatically track the curent item...