I think you can do this:
Create an instance variable for the object, "SineType" or whatever.
Create some events to change the sine type depending on that variable,
Object.SineType=1 ----->Sine
Object.SineType=2 ----->Square
Object.SineType=3 ----->Triangle
Object.SineType=4 ----->Sawtooth
Then,
Condition-----> Set Object.sinetype((rnum(1,4))
Something like that.
Edit: Actually I think it would be Object.sinetype(floor(random(1,5))