There's an example in the docs: HubAction Object - Hubitat Documentation
// Send UDP Message
new HubAction("My UDP Message", Protocol.LAN, [type: HubAction.Type.LAN_TYPE_UDPCLIENT])
// Send Binary UDP Message
new HubAction("48756269746174", Protocol.LAN, [type: HubAction.Type.LAN_TYPE_UDPCLIENT, encoding: HubAction.Encoding.HEX_STRING])
If anyone is using the ESP8266 MiLight hub, I wrote a driver for it (currently supports white bulbs only, but plan to add colour bulbs in the future).
The esp8266 hub is really good, and supports more than 4 light groups (like having multiple limitlessled hubs), as well as listening for messages sent by other remotes/hubs. I currently have an rpi listening for those messages to update light status in Hubitat - hopefully in the near future MQTT will be supported on HE to do this directly!