The 34465A has a clunking switch (as Dave calls it) to switch the terminal, it's not software settable.
They sell scanner cards, and even switch units. Something like the U2751A.
Of course you can build your own one, it's really not much effort. You can connect it to the two coax output on the back of the meter, the VM complete and the trigger, and turn it into an automatic scanning unit. You can even do this with simple logic gates, don't even need a microcontroller for it, just a 74HC4017 connected to some relay drivers.
Of course test automation is a whole job that people can spend their entire career doing just that.