Those are software limits, and I haven't set any.
They are just an additional feature to make sure your dish cannot be driven to the point of crashing in to a wall! I make do with the hardware limits on the motor alone.
It isn't very instinctive to figure out how to drive the Humax, and I'm afraid I would find it very hard to give you instructions, so the best you can do (and also the most worthwhile thing) is to play around.
The DiSEqC/USALS features are not the primary selling point for Freesat Products, so I suspect in the case of the Humax they are a legacy from their adaptation form similar Humax kit sold elsewhere in the world.
It took me a while to learn how to drive it properly, but once set up it's fine.
Don't forget you cannot get into the full non-freesat mode to enable other Satellites etc until you've first done a non-freesat scan on 28E: Best advice I can give is to confine that scan to the Sky News Transponder alone - not only is Sky News not available in Freesat mode, so is a useful one to have in your non-freesat list, but restricting the scan will seriously reduce the amount of channel editing (ie Deletion!) you'd otherwise have to do. And the scan fulfils the pre-condition for being able to use the Red Green Yellow Blue Green Yellow Blue sequence for accessing full non-freesat mode.
