SET codes are for the organizations to which they are assigned. If you are not part of the organization and you use the code you could be creating problems for yourself well beyond any savings which you might have earned. For starters, you could be asked for ID at checkin. When you don't have it, you may be looking at rack rate.
Additionally, organizations which share their SET codes beyond those people legitimately eligible risk having the discount reduced or cancelled. Posting those codes may also violate FT rules. I know that this has been discussed on FT a fair amount in the past. I'd check the rules. Then tread lightly.
You might ask one of the Lurkers for clarification on what is allowed and what is not.