I actually tried once to figure out if there is a way to extract files out of an installervise archive the way you can with TomeViewer and Apple installation archives. The short answer is I don't think you can. The long answer is I installed the mindvision software used for creating installation archives thinking it would perhaps let me open up archives created by others but it seems you can't (or else I could not figure out how to do it).

One thing you might try that has worked for me in the past is to just use resedit to change the version resource to the desired version number. In your case change Premiere 6.5 to 6.1. You may have to play around with the files to change depending on exactly what Premiere installs. For example, in some cases you can just change the version number of the main app but in other cases you may also need to change the version numbers of additional components installed such as extensions, etc.