Can't be done currently. Gap is looking into that possibility, but besides the technical issues (even the "official" LR diagnostics don't allow such a change) they are also concerned about potential liability of their tool allowing to permanently raise the center of gravity of these vehicles at high speed.
As mentioned above, you can recalibrate your suspensions to rise 2 - 2.5" at all heights with IIDTool, leave the suspensions switch to normal height and get pretty much the same result while off-roading since the car won't lower at speed (and with the added advantage of an extra lift when needed by invoking off-road height with the switch, which will raise your car to the rough equivalent of super-extended mode.) Use IIDTool again to knock them back down to factory settings when you are done wheeling. Takes only a minute. I use my Llams height controller switch instead because it's even faster than IIDTool, but the results are the same. I very rarely touch the factory switch to change suspensions height anymore.