In snowboard terms, a lipslide is when the back end of your board (aka, your tail) goes over the rail, and a normal slide is when the front end goes over the rail. Hardway 270 is when you spin into a rail with the back end going over first.
I don't see why this should be different on skis.
A lipslide going forward would take the back end of your skis (your tails) over the rail.
A switch lipslide would take the back end of your skis (your NOSES) over the rail.