Michael offers very good "been there, done that" information. He's just getting his back together after a broken chain.
Yes, you can roll in the chain by pulling the valve cover. Here's what you do:
With a new chain and two links on hand, use tie wraps around the chain and through the holes in the cam gear. These are so you can remove a link to attach the new chain. Use dremel tool with a grinding wheel to cut the pin ends off of a link. Make sure you cut the pins from the same link. Once the ends of the pin are ground off, pull the link out the back. Temporarily insert a new link into the end of the chain that is on the drivers side of the engine, and peen it into place. If you can get a clip mounted master link for this installation portion of the operation, it will be much easier. With the new chain connected the old, cut the tie wraps and turn the engine slowly CLOCKWISE with a 27MM socket on the front crankshaft bolt. Keep feeding the chain as you go, but keep the old chain engaged with the passenger side of the cam gear as you feed it off. You may need a helper to slowly turn the engine while you feed the new chain and pull off the old one. Once the new chain makes its way all the way through, tie wrap both ends to the cam gear again, that will keep the chain in place while you disconnect the old chain and put your permanent link in place to connect both ends of your new chain. There is a tool available to crimp the chain, but if your careful, you can use a dolly or big hammer behind the chain, while peening the ends of the link pins in place over the new side plate.
Now, this tells you how to roll in a new chain, but that will probably not fix the noise. The noise is probably due to the tensioner. If there is low oil pressure or a worn tensioner that will not hold oil pressure, the chain will slap. Additionally, it is possible that there is a broken or loose chain guide. Rolling in a new chain won't correct the problem, but it wouldn't be a bad idea to roll one in once you find and correct the source of the noise.
Hope this helps,