If you want to be able to easily customize the font size of the generated LaTeX, navigate after installing to:
   1. Your user folder > Library > Application Support > Adium 2.0 > Plugins > Latex Plugin.AdiumPlugin
   2. Right click, and get "Show Package Contents".
   3. Go to the Contents > Resources folder, and edit preamble.tex, and edit the first line from 12pt to your desired font size.

Requirements:

· Adium 1.3 or later