Expanding text lines from the middle

[mason_2932]

I'm trying to do a simple expansion of 3 lines of text but make the middle line the base so that it doesn't move, and the top line and bottom line expand in their respective directions but I can't seem to figure out how to use line spacing or leading to make the lines expand from anything other than the top line of the text.

[Airweb_AE]

Maybe by using 3 text layers and a slider to control the leading.

[Airweb_AE]

Or maybe even simpler, 1 text layer, 1 slider, and a text animator with an expression selector.