change gearbox from auto to manual

A lot of work. Not the gearbox part, the clutch assembly from pedal to linkage. Not sure on that model, but some require re-locating the brake pedal.

All he needs to do is get a Manual version of the brake pedal and a Clutch pedal with a master cylinder (if its hydraulic), with the entire clutch assembly. Also the shifter linkage assembly will need to be replaced. ECUs may have to be replaced as well. Most parts can be taken from a donor vehicle. I did a similar swap on a Nissan 300ZX a while back. Most of the modern Automatic transmissions are more efficient than their manual counterparts.

IMHO, it more trouble than its worth. It's easier to convert a RWD transmission than a FWD.

It used to be easy, because all Toyotas were stamped (firewall) with all the necessary pass-throughs for the clutch cylinder. Not so on twoI have looked at for conversion. My '88 Supra (auto) is set up to be converted, but my '95 Tercel was NOT, and my friend's 98 Paseo is not. This means punching a hole through the firewall, which I have been told is not a wise thing to do. If you look at a car with a manual, the place where the clutch plunger passes through is bossed and then punched. On the cars I mentioned above, there is not bossing, which means getting hold of a good-sized greenlee and punching one...but the angle may not be right.

Then there is relocating the pedals. You'll probably have to go junkyard diving to find a set of pedals, and then remove them. At least by removing them you'll get an idea of what you'll have to do to install them. As a number of people have said to me, sell the one you have and buy a 5-speed...

It takes considerable fabrication skills to convert an automatic to a manual, and vice versa. It would be cheaper to trade the automatic equipped car in for a manual equipped car of the same model.