I'm sure you could do freestyle slalom on figure boots with figure frames/wheels but certain tricks, mainly those involving the toe and/or heel wheel, would be harder/not possible as the toepick would get in the way and the heel wheel would be too far back. But there are lots of tricks that don't use toe or heel wheels in that way. I'm not sure exactly why you'd want to, though to be fair I try to figure skate on my inlines and adapt slalom tricks to my ice figure skates so who am I to talk?
The main difference in technique is that inlines don't have much of a heel so your posture is different over the skates - on inlines you have to make more of a conscious effort to pitch my weight forward, and I find figure skating moves like holding edges for a long time a lot harder. Obviously quite hard to do toe jumps on inlines, and spinning is harder as you don't have a spin rocker. I use rockered frames on my inlines which have a banana rocker. But anyone who can skate well on figures can do so on inlines, with a modicum of getting used to the different feel, and vice versa.
