Textual-Solarized is a Textual IRC style for OSX. You can find Textual at http://www.codeux.com/textual/ or on the App Store.
I have derived this from the Simplified Dark theme bundled with Textual and have applied some of the Solarized color scheme (http://ethanschoonover.com/solarized) to it.
Checkout this git repo into ~/Library/Application Support/Textual/Styles in a sub-folder and it will be an available option in the Textual preferences pane.
cd ~/Library/Containers/com.codeux.irc.textual/Data/Library/Application\ Support/Textual\ IRC/Styles/ git clone https://email@example.com/excid3/textual-solarized.git