You can use for aquisition of multiple channels AI Acquire Waveforms.vi. Then set the list of channels as for example
1,1,1,2
In this case per 3 readings of channel-1 you will get 1 reading of channel-2: in other words channel-1 is acquired 3 times faster then channel-2.
So you can create your own configuration of rate and phases of readings for different channels, for example
1,1,2,3,2,1,3,3,1
Oleg Chutko