Just unpack *.zip archive, obtain a *.pk3 file from it and do old-good drag'n'drop to "GZDoom.EXE". If you want to use it with other mods, just create a shortcut with "-File" parameter (.bat file is good too) or check out "ZDoom Launcher" (this is useful tool).
All minor and major fixes gonna be applied immediately and then existing files gonna be updated.
By the way, there is list of existing utilities:
Simple ACS script that gonna tell you if one of the map's milestones were achieved. It may be 100% kills, 100% items or 100% secrets.
This patch must be loaded before your beloved'n'chosen enemy pack as support that gonna got rid of any stinky stealth monster that was placed on map by...
This provides an additional event handler that gonna make every enemy along with destructible decoration drop something very useful.