Well, I too have no experience with SCI-Studio, but the basic seems the same as AGI-Studio. In AGI-Studio, I would use something like this (with lots of errors, but it's just to explain

)
if said("sit"){
set f(50) ------>expecting that you use f(50) for this.
//make ego sit
}
if said("stand"){
isset f(50)
//make ego stand
reset f(50)
else
print("You're already standing.");
}
Something like this, but in SCI-script should do the trick.