I assume you have the rulebook. It states you have to have 3 TD credits. One of the three has to be as the Chief TD of on Category D tournament and can not be substituted.
One of the credits has to be as the Chief TD or chief assistant TD of a different Category D tournament of at least 3 rounds and can not be substituted.
Only one of the 3 required credits can be substituted and only one from being a TD of a section of a multi-section tourney.
Based on my reading of the rugulations and the fact you say you only have been a TD in 2 events, you do not meet the requirements. I'm thinking that you only have 1 credit and must be a Chief TD of 2 more events to get the credit.
However, the best place to ask that questin is at the USCF.
http://www.uschess.org/component/option,com_wrapper/Itemid,327/
Be sure to choose the Tournament Directory Certification subject.
So far, I have been chief td of 2 sections but have never chief td'd a tournament. Do you know if this fulfills the "chief td of a category d tournament" credit required for local td?