How to run FFP Beta with the original Firefox installed and running

Thank you for the firefox portable!
I have installed original firefox 3.6.13 now in my PC, at the same time, I want to run firefox 4.0 beta8 for testing. When doing this, it came out a msg "Another instance of Firefox is already running. Please close other instances of Firefox before launching Mozilla Firefox, Portable Edition."

I had search all the forum and found no good solution. After change like this:

1. Close all instances of Firefox Portable.
2. Copy FirefoxPortable\Other\Source\FirefoxPortable.ini to FirefoxPortable (next to FirefoxPortable.exe)
3. Open FirefoxPortable\FirefoxPortable.ini in a text editor (even Notepad will do)
4. Change "AllowMultipleInstances=false" to "AllowMultipleInstances=true" (no quotes)
5. Save FirefoxPortable.ini
6. Repeat for all other installations of Firefox Portable
7. Run multiple installations of Firefox Portable

I could only start with the original

3.6.13 one with portable profile.......

Could anyone help me please? Thanks a lot~