Rodimus_2316: I think I was confused. Pressing "H" made me able to walk using the left-mouse button, but then I had to use the right one to do the other stuff. When I pressed "H" back, I walk with right-mouse button, but use the left one for other stuff. It's only these two options, I take it? If so, understand I haven't played this game in almost 30 years, so I must forgotten you can't do it all on one mouse button, as I guess the game needs to know when to move and when to examine, move, take things, etc.
I'm unfamiliar with the mod, but I know that, traditionally, for Ultima VII, you use the right mouse button to move and the left button to interact with things.
Specifically, if you place the mouse over a location, if you click the right mouse-button once, your character will take a single step towards that location. If you click the left mouse-button once, you will look at that item and the description of the item will pop up.
If you click and hold the right mouse-button, you will continuously walk in the direction of the arrow until you hit a barrier. If you click and hold the left mouse-button, you can move an item from one location to another.
There's also double-clicking the left mouse-button to use an item. Double-clicking the right mouse button doesn't really do anything.
So...I don't see how you can map all actions to just one mouse button without some more significant coding. I think you can just switch them, or you might be able to macro the left or right mouse-button to a keyboard key.