Fiddled with this before. Don’t have much to offer, though! In general t-max intervals are just intense VO2max workouts & there is probably a reason why we heard a lot about them for a while and not much since then. I’ll say this…
1.) This is easier to do on TR since they adapted a MAP ramp test as their primary testing tool. PPO is almost always 130% to 135% of your ramp test MAP. So if you say your TR ‘FTP’ is x your t-max power level will fall somewhere between 1.3x and 1.35x. Or you can look at the highest power step in your MAP test. Or you can look at your max 1min power in your MAP test. Whichever…it won’t be too different.
2.) I would not advocate this approach as an ongoing training approach. Do it once in a while for a few weeks.
3.) I would periodize it similar to what Ronnestad did with HIT sessions for cyclists. Week 1 do three sessions. Week 2 one session, Week 3 one session. Further, Week 4 I would switch back to some of the longer Seiler intervals (let’s say his 16 minute interval or even the 20 minute stuff he used to talk about in the 90’s)…to sorta capture the effect Seiler saw in his intensity mixing study. And then just a week of recovery before a target event.