it is much easier if you take the carbs off first so you can change the screws to the allen ones making future changes much easier. You also learn a lot about the carbs and your bike doing this as well. But your call.
You can do it with the carbs on the bike. It just takes small fingers and a really good phillips tips. The original phillips screws strip very easy and they are kind of hard to get at. Use a small ratchet with a phillips bit, or a 90* screwdriver and you can get in there.
