I'm sorry, Dan, but that's not even remotely possible!
The programs are extremely different. (Premiere 6 was discontinued when the Pro version of the program was developed in 2004 -- so that file is nearly 10 years old.)
In fact, most Premiere Elements users recommend against even trying to open an early version of a Premiere Elements .prel file with a newer version of the program.
Welcome to the forum.
As Steve says, Premiere (precursor to PrPro) Project files will not open in PrE.
With certain limitations, a PRJ file will usually Open in a later version of PrPro (the files are PRPROJ in that program). If they will not Open directly, then one can usually Import the PRJ file into PrPro.
The closest that one can do with PrE would be to Export the Timeline in Premiere, as say a DV-AVI, including the edits, and then Importing that AV file into PrE, for additional editing. This is true for all versions of Premiere/PrPro.
PS - so long as the PrE version, and the PrPro version are close, one can often Open a PREL in PrPro, but there are some caveats: Themes/Instant Movies will not work, and many 3rd party Effects/Transitions will also not work. However, with a simple PrE 9 Project, one can likely Open that in PrPro CS 5/5.5. If the versions are too far apart, then ALL bets are off. I can Open PrE 4.0 Projects in PrPro 2.0, but with PrE 8 Projects, I cannot.