What they mean by ink gel medium for acrylic is the sort of gel medium that increases fluidity and drying time. They are usually self leveling too. There are all sorts of kinds. If you look at this Blicks page (click here)
, it has many different brands and such.
I have tried acrylics for printing, using a cheap craft brand that is very liquidy. It didn't work that great but it wasn't that bad either. I was using it as part of a design and not a stand alone print so it was alright that it was patchy.
I think if I did it again, I would use a better paint with a gel medium.
You could experiment using small linocuts just to get the feel for it and see if you like the effect. Be sure as acrylic does dry quickly to have either a sink full of water ready to rinse off your lino or a bucket of water or something by you to dunk it in so the acrylic doesn't dry on it.
Be sure to show us what you do too, I would love to see it.