i see 2 related questions here.
1) how to take a loss in NT when there are no capital gains during the taxation year.
ans: already posted (losses can only be netted against gains.)
2) how to take a loss in NT at any time:
ans: if there's no OTC market taxpayer has to "sell" the stock to generate a loss, presumably to a friend or relative who has an account at same brokerage (broker will charge a fee.)
note: unless he intends to carry the loss back to gains in prior years, it's probably better not to sell for a loss this year, because tax consequences of a loss carry-forward are not quite as beneficial as netting a loss against gain in same taxation year. Just carry the miserable thing forward.
if he never has any gains i won't dare to ask what's he doing in NT in the first place ...