Joel,
One more thing.  Since the hardware does not support the analog triggering then we can always implement a software equivalent.  You could monitor the voltages that are being read by the DMM and throw out all readings until the readings are above a certain threshold.  This would have the "effect" of an analog trigger but without the hardware timing.  I hope this is an acceptable workaround and please let me know if you have any further questions on the matter.
Best Regards,
Jeff Tipps
Applications Engineer
National Instruments