Linphone works great
Linphone is an open source (free) AoIP app that runs on anything from WinXP to the latest Android and Apple OS. It can connect to another computer running Linphone but does a great job connecting to a Comrex. You can set up a SIP account for free or, if you have a static IP, connect directly to the studio unit. Just take a laptop to the game with a mic and headphones and connect over WiFi or wireless. I've done two hour broadcasts using my phone as a hot spot without a glitch. For information on how to set it up see the white paper on the Comrex website.