crwjerk,
it takes less than a minute to figure out that A330 THS setting is a linear function of MACTOW. So if the LTS software uses a formula, why can't you use it yourself when it is that simple? It is an approved method as this is the exact formula not an approximation.
AND...you primarily get your THS setting from the ECAM not from the loadsheet.
What michelda said is 100% correct (for all A330 variants) and I'd just add that your trim would be always UP (or zero).
