It's an adaptation of the original smali mods to the Google Calendar found here by @shaftenberg. There's preferences to allow you to customize how the event text looks in Google Calendar month view.
Tested against Google Calendar 20140414.
Standard xposed module stuff; install Xposed Framework, enable app_process, reboot. Install this module, enable in Xposed Installer->Modules, reboot.
Also available in the Xposed Repo.
Source is available at my github
(screenshot of calendar borrowed from shaftenberg's post)