I managed to input and record external audio in Resolume Arena.
Install http://www.jackosx.com/
Run JackPilot
Select your soundcard
Open Resolume
Choose Jackrouter as your soundcard
Trigger any audio or audiovisual clip
Add the Jack-Insert vst to it
Return to your Jackpilot window
Click on Routing
Route System/Capture_1 to Arena/VSTReturn1
Route System/Capture_2 to Arena/VSTReturn2
Route Arena/Out1 to System/Playback_1
Route Arena/Out2 to System/Playback_2
Ok, now your soundcard input goes to the VST Jack-Insert in the clip you triggered in Resolume. So you got an external audio input in your composition when that clip is running.
Hit Record button and you will record your video composition with the external audio input together.
You could also virtually route any OSX application audio or individual channels form Ableton Live to that VSTReturn in Resolume, with this great and freeware JackOsx.
Cheers
Leon Yamani