Select animation frame & frame display by default

Hello,

Is there a way to control the current animation frame being displayed, using the API (external buttons on the embedding web page)?

What I want is to be able to do a presentation of a process, which is done in multiple steps. Currently I can do that by changing the time display from minutes:seconds to frames clicking on it (eliminating interpolation) and then selecting the frame on the timeline, but it would be really helpful to control it by buttons.

It also could be done hiding and unhiding objects, but this makes the file bigger the more steps I add.

Thanks.