What you probably want to use is modelsUnderLoc(). When using
the #detailed flag, it returns a list of models under a 2D
sprite-relative point (which can be the cursor location). Check out
the documentation on this method.
Then use the #detailed info to determine if/where on the
plane the cursor is intersecting. The property is iSectPosition.
Use the vector derived from iSectPosition to determine your UV
coordinates for the texture (probably just multiply it times a
float to get it scaled properly).
I used this basic procedure to drag models onto a plane, but
the concept should apply to texture coordinates also. Though note
it can get tricky when you drag the cursor off the
sprite/stage/window, when to stop dragging, etc. You need to setup
all those little caveats.