Start slideshows on last viewed item

I would like to be able to return users to the same item in a slideshow that they were viewing when they last exited the same slideshow. Specifically I have several imagefields which rotate in a slideshow of postcard size images, each linked to its original node which then displays more information about title, date, author etc. I would like to be able to then return to the slideshow at the point at which I left, viewing the same image, then fading into the next and so on.

Presumably there is a 'counter' variable in the code which would need to be replaced and stored in memory on a per-user, per-session, per-slideshow basis and then called automatically. I'm no expert at PHP but if someone could point me in the right direction I might have a go at writing a custom function for this.

Fantastic module by the way - thanks.