Hi @CabbageCrazy, are you using the latest version of Cabbage 2? If not go here and grab yourself an installer.
I managed to get hold of a machine with Live and was able to try out some things. I couldn't get Iain's MIDI effects to work, but it could well be a user error on my part. I did however dig up a simple MIDI arpeggiator I wrote some time back for a student. I've attached it here.MidiArpSimple.csd (755 Bytes)
I can't say why your instrument doesn't work without seeing the source code, but it might be that your CsOptions were not set correctly, you have to use -Q when you wish to output MIDI. Anyhow, once you have placed the MIDI effect on a track in Live you just need to make sure your receive notes from that track in the synths you have. Below is a screenshot of a simple Live session that has an arpeggiator on track one, and a synth on track 2. The notes from the arpeggiator are being fed to the RingMod synth. It all appears to work fine for me in my simple tests. Let me know if it works Ok for you. Feel free to modify the version I've attached to suit your own needs.