First, skip the veggie oil. Second, if the pieces of retained shed are going all the way around the body and could contrict blood flow, soak the snake in tepid water for approximately half hour intervals in no more than 1" of water, then use Jotay's towel trick. Third, if the retained shed is not going all the way around the body, leave it alone on the belly because you might end up pulling off new scales in the previously burned area if you get too focused on getting the old skin off. If you make sure your humidity is good for the next shed, it should come right off with it.