Midi multi-channel pitch mixer

We're trying to adjust the pitch on multiple channels and then storing the data for each channel in a multislider object (with channel one being index one of the input list, channel two being index two, etc). What's a good way to construct a list of pitch information for the different channels so that each channel can be changed and not affect any others?

We tried using vexpr to take the list of values from the multislider and then add a list of all zeroes except for the index that we want to change, but this did not work, so we're looking for alternative ways to accomplish that.