The quick answer is find the path to the Maelstrom.exe you want to run on your machine (where did you put it?). Find the ERAS path for the Program/RESOURCE folder (where did you put it?). Then modify a Windows Shortcut with the Target = the path to the Maelstrom.exe you want, and the Start in = the path to ERAS stuff.
Use the shortcut to launch the game.