Jon has it right - the addition of more manifolding, solenoids, wiring and switches is what it will take. One owner and forum member did his own a few years back. My guess is a couple hundred for the materials and several hours labor. Give a call to Lippert to get a better sense of what it will take from a materials and cost perspective.
Someone mentioned their entry level RV had individual slide room controls. I'm wondering if that trailer had electric motors for each slide - not hydraulic rams. As an example, our early Sundance 5th wheels were all electric slides at one time. Hence, each individually controlled.
Most of our bedroom slides across nearly all brands are now electric. That's why in some of our brands where the rooms are not individually controllable, that the slide room is.