It's pretty darn easy on a 240, especially a SOHC. Got plenty of room to do it with the engine in the car.

When you go to your new friend google and do a search for it, the write ups you find may or may not instruct you to remove your intake mani. I would recommend removing it to make it a bit easier to handle everything.

Also, while you're in there, you might as well spend a little extra cash on parts and go ahead and do all of your gaskets (intake/exhaust mani, valve cover). Would suck to just have to take it all back apart a few weeks later when an exhaust mani gasket decides that it didn't like being moved and you get the oh-so-annoying tiny exhaust leak.