I wrote this program up real fast, it will allow you to go through each frame manually and write down which frames do what.
input "Object filename -> ",filename$
sync on : sync rate 0
load object filename$,1
currframe=0
totframes=total object frames(1)
do
if spacekey()=1 and pressed=0
pressed=1
inc currframe
if currframe>totframes
done=1
else
set object frame 1,currframe
endif
endif
if done=1 then text 10,10,"End of animation"
text 10,30,"Current frame: "+str$(currframe)
if spacekey()=0 then pressed=0
sync
loop
Also, if it's a gun you have, you can just look in the file called 'gunspec.txt'. Near the bottom there is a list of animations with their start and end frames. Characters have a similar list in their .FPE files, but the animations are not clearly named and so are pretty much unidentifiable.