techdooh.txt:

This prefab is tech-style 4-way hatch door created by Hugo Tremblay (hugo.tremblay@tr.cgocable.ca.)  If you want to use it in your own maps, here's all you have to do:

1.  Unzip the prefab into your BSP directory or make a subdirectory under C:\BSP called \prefabs if you want to keep them separate from your BSP files.

2.  Load your map in BSP - make sure no brushes are selected

3.  Select Objects/Merge in... from the File menu

4.  Find the file slipdooh.mrg and load it in.

5.  Go to coordinates 0,0,0 and find the prefab.  All the brushes of the prefab should be selected for you.

6.  Select Texture Lock/Lock from the Edit menu

7.  Drag the selected brushes to the location where you want this prefab to be in your map.  Note that this prefab is entirely composed of entities, so texture locking won't work.  After you drag it you'll have to adjust the textures manually.

8.  This door is set to open by shooting it by default.  If you want to change it, you'll have to change the entity keys.