Of course it'll work.
If you use the 2nd psu method, you're just doing manually what the timer does automatically.
Just use a 2nd psu first, and use a stopwatch or similar to find the time it takes for the Mach1 to cool down, add 20-30 seconds to that, and set the timer for that time. Make sure the time you measure is from FULLY warm with regard to the Mach1 though, if you measure from partially cold, you won't get a true reading and when you DO power up from warm, as in after a day of sitting unused, you could be booting too hot and damage your cpu.
The first time you use it with the timer, watch it carefully to make sure it's cooled down enough to boot, and you're set.
Gray