Technically the field is listed as not scriptable because the new value does not get stored inside of the save files. What you could do is create a value in the editor somewhere & then you could edit the first frame of the animation you want to control the delay values of & create some actions for it...
if value "animation_speed" is '1'
execute a script > Animations["example"].AnimationPause = 100
end if
if value "animation_speed" is '2'
execute a script > Animations["example"].AnimationPause = 200
end if
if value "animation_speed" is '3'
execute a script > Animations["example"].AnimationPause = 300
end ifValues do get stored in save files, which means each time the animation starts or loops back to frame 1, that it will check the speed it should be playing at.
P.S: I use a similar method (minus the values) for a faster walk speed when someone double clicks instead of single clicks.