You can change "void" to "function", but i dont know moore about c-script.

Have a look at the line

vec_lerp (Temp_vec3,Temp_vec1,Temp_vec2,random(1));

from my Code. vec_lerp gives you a random Point (Temp_vec3) between the two Points (Temp_vec1 and Temp_vec2).

I use this code also to show up a sword particleeffect.