You can do it the Renault way with the pulleys locked as many have I'm sure if the timing was spot on (hence the large numbers of poor Dyno results and poor idles) and take the chance it was all perfect before and it won't move even a little bit once it all settles in (unlikely) but why not just loosen the ruddy pulleys and make sure it is all equal. Engines that have keyed pulleys are not that timing sensitive and can get away with it and so are no comparison.
Most of the 8 valve engines I've worked on (all keyed) use the same timing marks regardless even if you skim the head to it's limits as the tolerances were ridiculous. Played right into the hands of the tuning companies as your standard timing could be complete rubbish and then you'd get a performance cam and time it in properly with a vernier and then tune it further on a rolling road. You'd get fantastic gains if your engine was running pants before.
Some engines had pulleys with the keys in different positions so that for restricted race series use you could make sure the timing was spot on. Cars going to the shops didn't miss 5-10bhp.
For all we know when this person goes to install the tools he may, as many have found that the timing is already out and he'll have no choice but to loosen the pulleys anyway!
If the dephaser is worn he'll have no choice.
Use the Renaults guides. Follow the pointers that the traders have released over the years, use the correct tools and it will be fine. As I said if the tools fit properly at the end and the tensioner points where it should then the jobs a good'un.
Me personally if I'm doing something DIY I do it properly especially if I have the time to really go to town on checking everything.
