Thanks for your interest in the source port and apologies for the (very) late response.
To run the source port on Windows, you download the zip file and extract the files to a location of your preference on your hard disk. Then you run the CatacombGL executable. When started, a selection screen with an overview of all the supported games is shown. In case the Catacombs Pack was installed via the GOG installer, the game data will be auto-detected. Otherwise, it is possible to manually browse to the folder which contains either the Catacombs Pack or the shareware version.

At this moment the latest version is 0.5.6, which was released just a couple of days ago.