Populate a custom field from a mysql table

Each post has a custom field of “votes” that is automatically created. In my db, there is a table called “wp_votes” (unrelated to the custom field).

What I want it to do is this:
When the DB table “wp_votes” is increased by 1, I want that new number to be inserted and saved into the respective posts custom field of “votes”, overwriting whatever was in that field before of course.

(This is in conjunction with the vote it up plugin which has functions that I can’t even begin to find explanations for. Apparently the only thing I can find are posts where people are more confused than I am.)