As far as I have seen last around 10 years, TN visa adjudication is lot more rigid. Substitution, equivalanecy and evaluation as same or similar, has limited success.
If you are taking a diploma route, then try to meet the requirments of that. Dont try for what will acceptable and equivalanet. H1b is lot more open to substitution and equivalency than TN.
So try diploma+3 years expereince and diploma should be from North America and should be two years, also be careful law says Post Secondary diploma, in IT or related field and so should be the experience.
I am assuming you are trying for Computer Systems Analyst, if you are trying for Software Engineer, this wont work. Make sure the title and and work description is clear in those terms.