Yes for Serial and IP, and assuming you are using a supported infrared adapter then yes for infrared as well; however, you should be aware that it can be a somewhat technical process.
If you have infrared codes for your device in either ‘Pronto’ flat format (each code usually begins with ‘0000’), or in Global Caché format (each code begins with a frequency number usually close to “38000”), you may add them to your RoomieBackup.zip file and then restore it to add them. Adding a code set to the codes key of your RoomieBackup.zip file (and then re-zipping it) will cause Roomie Remote to import any enclosed commands. It is even possible to override the commands in Roomie Remote’s internal database with your own commands by matching the brand, model, and make of the device you want to update.
The Roomie Remote DDK shows how to construct custom command additions. The format is identical to Apple’s plist format derivative of XML thus allowing you to use many widely available tools to edit such files.
It is also possible to add support for IP or Serial devices. This uses the exact same process as the infrared codes above and examples for this are provided in the DDK. If you are adding devices that Roomie Remote doesn’t know how to Auto-Discover, you will need to add the device via the Add Device Manually option.