Possible to assign a value list to a field via a script?

I have a file I call Instruments (as in psychological ones, not musical!) which has two tables: scales (for the names of scales) and stems (for the text of each scale stem). I have another file I call Assessments, which is where the data field resides for all responses to any of the scales.

I envision creating a script which would call up in one portal the assigned scale, showing all of its stems. In another portal, I would like to show the required number of rows for the data which would correspond to each stem. The challenge is that each stem can have quite different answer sets, e.g. one might be the 'strongly agree - strongly disagree' type while another could be 'almost always - never' type. Is there any way to link value sets to the stem to pass on to the data field in each applicable row?

scale portal data portal

stem 1 wording data field ( needs SA - SD value list)

stem 2 wording data field ( needs yes-no value list)

stem 3 wording data field ( needs almost always - never value list)

Thanks for any assistance!