Change Qty select style + add variable

Howdy.

I want to see if there's a way to change how this Quantity selection works, from a number input field to a quantity dropdown selection. Ideally it would:

1. Allow the user to select a preset quantity of 1 to 5 units
2. Allow the user to select an "Other" or "More!" option at the bottom of that 1 to 5 selection, which would prompt the field to revert back to the original input field

Any help would be appreciated, even if only part of it can be accomplished with css, javascript, or some combination thereof.

Haven't been able to find a solution to this on my own. Any help/direction would be appreciated.

Still haven't had any luck; tried a couple things with innerHTML replacements.

@paul2009 or @tuanphan have you experienced this request before? Apologies for the mentions outside of a thread y'all are active in. This one's just bugging me and y'all are the experts 'round these parts.