You can use this to reverse scroll direction (natural scroll):
xmodmap -e "pointer = 1 2 3 5 4 7 6 8 9 10 11 12"
You can also set it back again with xmodmap -e "pointer = 1 2 3 4 5 7 6 8 9 10 11 12"
and this to switch the left and right buttons:
xmodmap -e "pointer = 3 2 1"
And change it back with xmodmap -e "pointer = 1 2 3"
But how do you enable tap to click from command line? Preferably with one command, and not permanently.
By the way, yes I do know this exists: