I think your confused what is vb
and what is photopost here at this point. We dont have an impex script nor is anything your doing with Photopost have to do with that script. If your trying to setup a test copy of Photopost if your dont want to upgrade the existing site you need to do so manually.
You must follow the documented instructions with our package for upgrading a Photopost install from 4.66 to 5.3. An Upgrade means you upgrade an existing functioning Photopost Install and the documentation outlines the steps. Yes the file structure changed with Photopost 5 series.
You need to run the upgrade on a working Photopost 4.66. Whether it is the primary one or a secondary one I leave up to you. You do not delete files or directories. Just follow the upgrade instructions to upgrade your Photopost.
Once you upgrade you can go about the switching integration stuff that has been discussed.