In case you haven’t been paying attention, @geko discovered raw data is possible with the sendHub command. The following works with iTach:
sendHubCommand(new physicalgraph.device.HubAction("""$theCom\r\n""", physicalgraph.device.Protocol.LAN, "${deviceNetworkId}"))
where theCom is the iTach command string, and deviceNetworkId is the ‘iTachIPAddressConverted toHEX:1386’