Excuse the late reply.
It should work out using the instructions you listed above.
Do you not see the Quick Time 7 checkbox when following these instructions?
Also, in order to get the functionality of the Pro version of QT7 you will probably require one of the Pro Apps installed on your system (Logic Studio or Final Cut Studio) - or to purchase QT Pro from Apple.
Basically Quicktime is the engine upon which iMovie, and iTunes even, is built on.
If you're happy enough with the workaround solution then maybe there is no need to install QT7 Pro...