I've heard it's a pain to do an m103 serpentine belt and tensioner...

[WANT '71 280SEL]

What parts do I need to get this done? Fastlane lists an idler pully and I believe an idler tensioner? Or something along those lines. How long would I be looking at to do this task? I know I need a belt, what else? The car has an intermittent squeal. Is it like newer American cars (or at least GM) that you just need a break-over bar with something like a 15mm at the end?
Thanks
David