Hey,
It is totally possible in LabVIEW. I don't have the drivers on this machine, so I can't tell you exactly how, but you use the sub-vi that configures each channel for scanning. You only have to setup the channels once. If you take a look at the manual where it gives you the commands for setup and scanning the channels, and then compare them to the NI drivers for the DAQ unit, you'll see they are setup the same way.
However, remember, you are limited by the speed of the switching unit. If it says it has a maximum of 250 switches per second between channels, then that is the fastest rate you can sample data, even though with one channel the sample rate is higher. I don't know which switching unit you have (since there are several options for the 34970A), but the info on each of them is also in the manual.
Good luck!