One thing to check out is Peter DeBaets Drag-N-Dropper program at:
It's good stuff. Allows "text to be moved or copied (using 'CTRL-Drag') between text-based MS Access controls (including single select list boxes) by clicking on the desired text, dragging to the new control, and releasing he mouse button."
Demo available to play with.
I've never tried writing code to do what you need but hear it's a nightmare.