After Effects: Trigger change at timecode a condition becomes true?

So the other week we figured out how to mimic the mouse-hover functions in Windows 10, by setting the opacity of a highlight to change when the mouse cursor is over it; now I'm looking to do something similar, but a tad more elaborate.

Now I'm building a mock webpage, and I want to do that thing where the an object enlarges a little when the mouse passes over it. I've already got the element in place, now I just need to see about making the size change.

The quick way is to use a variant of the solution provided by Dan Ebberts for the other question, which would set the scale to 100% when the mouse is over it, and to 95% when it's not. That's good for a "snap" effect, but I wanted to know if it would be possible to get it to change over the course of a set number of frames (in other words, when the PNG for the mouse cursor overlaps with the PNG for the web item, have the latter increase in scale by five percent, over the course of say ten frames, and then shrink back down over the same duration when the mouse cursor is no longer overlapping).

This is a very specific thing and I know it, but I'm slowly beginning to realize After Effects is a lot smarter than I thought (and WAY smarter than I am), so I'm trying to go all-in and do as much as AE can support.