3DSMax exporters should arrive in a zip with this content:
1) Copy all the *.mcr files to <3dsMax Install Dir>/ui/macroscripts
2) Copy PSMaxMenus5.mnu to <3dsMax Install Dir>/ui (if you have 3dsMax 4.0 don't import this menu definition, but add them manually)
3) Launch 3dsmax, go to Customize->Customize User Interface. Select the "Menus" tab and click on "Load...". Select the PSMaxMenus5.mnu file.
4) Close 3dsmax and open it again. You should now have a PlaneShift menu in the main bar.
Note: The PSMaxMenus5.mnu seems not to work on all installations if imported. The error given is a syntax error while parsing the script file. If this happens perform the manual installation steps:
0) Remove from <3dsMax Install Dir>/ui/macroscripts the mcr files you copied before. So you will not have any PlaneShift mcr files there.
1) Copy all the *.mcr files to <3dsMax Install Dir>/temp/ (create the dir if not present)
2) Launch 3ds Max, press F11 (to open the MaxScript Listener Window)
3) "Open File..." select one of the mcr files in the /temp/ dir. Example exportCSP.mcr
4) Click on "Evaluate All" in the window of the loaded script. This will register the script.
5) Click on Customize>Customize GUI.
6) Select the tab Menus, then create a new PlaneShift tab.
7) From the left side of the panel drag and drop under the PlaneShift tab one of the scripts you Evaluated before.
8) Do the same with the other scripts. You should now have a new menu in max with the loaded scripts.