Yes you can program a 4th to 3rd downshift in lockup.
You can set the unlock speed, but no there is not manual lockup. I suppose a lockup switch could be wired in parallel with the towloc and it would probably do everything you want. There are very few functions that is won't do. Like I said, there are a lot of wire connections to make on install, so I paid a pro to do it, but I sure do love it.
KEEP ON TRUCKIN'
Lonestar