Can you control timeline the programmatically?

I want to be able to either start a slide's timeline at the beginning or jump to the end based on the value of a variable. I am trying to work around Storyline's limitations in HTML5 (the audio will not play properly in slide layers so I have to "fake" layers by jumping to a different slide then back again.) However I do not wish my users to have to rewatch the same "Launch" slide every time they come back to it. The slide properties allow me to choose to always reset the slide to an initial state or always play from the last state but I need to be able to choose this at runtime. The "automatically decide" setting always seems to choose the last state.

So what I would like is a way to set a variable when a user goes to one of my "fake layers" that would handle this choice.

Is this just beyond SL's capabilities?