I have a feeling your using a stock character? If so, make backups of your original files. I took "Aiko(unarmed) from scifi and looked at frame #168. Yes,it looks like she's sitting. The .fpe file goes to anim=91, I just added an extra (anim=92 168,168)
You need at least two frames for an animation (start & end frame).
This way I didn't change my original .fpe (just added to it).
Then for my script
:state=0:state=1,animate=92
At first she didn't sit, but after running the cleaner & saving level she was sitting down.
Beat me to it Rolfy. I was thinking couldn't he export the mesh at that frame and make it static? Since it wont have any other animations? Forget it, I remember, you can't export in while anim mode.