Fitst off. Get your led kit from Cointaker.com. Even though they both come from Cointaker, Marco has them but I found some of them are older kits and not as good as the ones I get from Cointaker.com. Pinsiders get a discount at cointaker. Just type PINSIDE in caps at checkout in the coupon code.
You will need a 1/4" magnetic nut driver.
Start with the GI ( General Illumination) lights. These normally run up each side and under the sling shots and return lanes. Do these with the power off.
Then do the inserts. The kit comes with a list. Put the machine in the single lamp test and lift the playfield up. Cycle through each lamp and replace them with the led's on the list. The list is in order as you cycle through each lamp.
Then do the flashers. Put the machine in the coil/flasher test and cycle through each one and replace them with flashers. Don't forget the ones in the back box. I'm not sure on Iron Man but I think the coin door must be closed for the coils/flashers to work in the test.
Then do the back box GI lights.
It's good to have the manuel with you to find the locations of bulbs or flashers that are blown. The number of the bulb or flasher will be listed on the DMD during the test.
Then after your done...look it over. Then you can add accent lights with color in the GI as most kits come with just white for the GI....I like to add some colored led's under ramps and plastics to give the game a little more color. You can also change white insers to any color led you want.
Have fun with it. Good luck. Show some pics when your done.