Arm Start trigger (work-around) for analog-input task

Greetings,

I have two counter tasks: ctr0 produces a continuous square-wave, ctr1 produces a GUI/user-initiated pulse. I would like to Arm an AI task on ctr1 pulse (rising) and Start the AI on ctr0 (rising).  The problem is Arm-Start doesn't seem to be valid for AI tasks(?)  Is there a work-around - that does not require using another counter? 

Thanks!