I reread your original post. You're want to use Ableton with your rack. Cool.
Here are some ideas.
The Expert Sleeper modules are very good when it comes to interfacing with a DAW.
The FH-2 and newly release ES-9 are worth checking out.
The FH-2 converts MIDI to control voltage. The 8 outputs can be set up as either gates/triggers or CV. So any combination is possible with CV, gates, clocks, etc. The FH-2 is also expandable if you need more outputs.
The ES-9 skips the translation from MIDI CV and acts as a direct gateway between your DAW and your rack: audio, CV, gates in both directions.
They aren't cheap and they aren't exactly easy to set-up/edit, even when using the browser interface. But they are very powerful. I'd do a little research on them as well as any alternatives by other manufacturers.