FWIW I think he means doing it by using the screwdriver down the plug hole to find TDC, wouldn't work to use one down the timing pin hole......
It's not like sticking a dial indicator down there, but you might be surprised how close you can get to exact TDC that way. Even with a dial indicator it takes a bit of back & forth wiggling to find the "center" of the piston's "dwell" at TDC. Fingers work quite well at feeling for the right spot.
If you need to do a "quick & dirty" belt replacement, where you leave the adjustable cam gears alone & just slide the belt on once you get the basic timing position for the crank & cams set up, the "screwdriver method" is adequate to get the cogs in the right notch & get the thing running!
Older engines weren't timed any better than the closest notch, and anyone who's done one of those would know how to get the Zetec timed that well.... Once the cam gears get their initial "set" at the factory, unless the engine has been rebuilt timing variations from a different belt will be minor. Nice to get it 'exact", but it should run fine with the original adjustment left alone. In fact, the "cam bar" is only NEEDED when you are resetting the cam gears since you can eyeball the cam position by the notches for the bar close enough to get the new belt in the right notch on the gear.
Certainly not as easy as when everything is locked in the right position, but certainly "doable".