I don't see any option in the articles manager or the article area itself to link to the built in rockslide, the only way I know how to load that is directly through the module position, but I see no option in the articles area to send the article to that position.
Because the option is not in the articles area.
The way it works in Catalyst at least, is that you drop content into a particular module space in the template, and this is picked up by the slider and reformatted.
So - what you actually want to do, is set up a 'newsflash' module, in a particular module slot that's described in the Replicant documentation as being set aside for the Slider. Set the Newsflash module to drag content out of a specific content category and set that content to publish at a particular time. You might have to do a bit of fiddling and re-think the way you deploy your content ... such as ALL timed articles go into the same category and activate / deactivate at different times. If you want to archive "once-upon-a-timed" content outside of the module, you may need to set up a second category with the same content on a different timeline.
Said fiddling is going to be a whole lot easier than trying to re-code the Slider though.