I am guessing he means on an engine out service, to lock the cams in place when removing the cambelt so that the timing remains unchanged. I did see one of these once but cannot recall the title of that thread.
When you have to positively lock the cams You make your own Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
You only need to lock the cams when removing or torquing the pulley bolt. It's probably safer to lock them when just changing the belt, but I don't think its necessary if the engine is at TDC. Mine certainly didn't move on their own.
If you are changing the t belts on a 355 you do not need the cam locks as the cams will not move (due to its hydraulic lifters) but on a 348 , with its solid lifters you will need to lock the cams or they may move. Its a shame Ferrari did not copy the NSX design where by the cams are pinned (holes drilled into the 4 cams where you inserted pins to lock the camshafts) for the t belt change. There is no way you can mis time that motor.
having timed a few 355 motors I can say you do not need the cam locks....the hydraulic lifters bleed down and nothing moves when the belts are removed. there is no issue here.