All I can tell you is that I have successfully taken a third party door open/close animation provided in a .x file and after running through Mender and loading into Animer, it worked. The resulting saved file from Animer was successfully loaded in FPSCR and animated fine. I only had to specify the animation ranges in the fpe file and then use the door script and it worked just like any other door, including the key functionality. Btw, the door I tried was from Arteria3d.com.
System Specs: OS - Windows 7 Home Premium 64-bit SP1, CPU - AMD Phenom II X4 945, 3.0Ghz, RAM - 8Gb DDR3, GFX Card - 2048MB NVIDIA GeForce GT 640, FPSC-R Version - Beta 1.007