This is a decent project for some looking to save a little cash. I believe my total cost for everything came to right around $100.
Sand paper: I used 180grit, 600grit, and 2000 grit
Paint: I used DupliColor rattle cans which can be had at most local auto parts stores for ~$7 a can. I used 2 cans of their scratch filler primer, 2 cans of their Ford Metallic Silver*, and 2 cans of their clear coat.
*Note that this is not a legit, true color match silver but I decided to give it a shot. It ended up being practically spot on, I can't tell the difference. I found a website that does sell perfect color match paints in spray cans if you'd like but it's about $20 per can. HERE
Cheap Ebay Mirror covers. I bought these for $42 shipped, they attach using supplied 3M double stick tape. Mirror Covers
First, as you probably figured paint doesn't stick to chrome very well. I had recently been doing research on how to paint the chrome Silverado grills for my brother's truck and found that most suggested sanding the chrome to a dull finish using 180 grit sand paper and for them it's been holding up well. So that's what I did.
Next, primer. You'll want to wipe everything down with mineral spirits or some sort of wax/grease remover. I started with light coats, eventually getting a little heavier with each pass. I applied 4-5 coats of primer, allowing about 10 minutes between coats. After that I let it set up for the recommended 1 hour(per the can) before sanding it down with 600 grit. When sanding the primer with 600 you won't have to apply much pressure, just let the paper do the work. What you're trying to do is remove any of the orange peel texture from the primer.
Once you've done this wipe the part down with mineral spirits again to remove dust or any grease/wax left behing from handling the cover. Then start with your paint coats. I did 5-6 coats with the paint starting with a light coat then getting a little heavier as I went along allowing ~10 minutes setup time between each coat. Mind the corners and edges, too much paint will cause a run, too little will cause it to be thin which means when you wet sand you could sand through the clear/paint to the primer. Just something to keep in mind.
After you've applied enough paint let it set up about 30 minutes(again, can recommended) and begin with the clear coat. I applied 7-8 coats of clear, starting off light and increasing in heaviness as I went along. Once you've applied the clear you need to allow it plenty of time to setup and harden before going further. For reference I finished mine Sunday night and waited until Monday evening to go further.
Next, wet sanding, compounding, waxing. I used 2000 grit. Some people start with a 1500 grit, then go to a 2000. Either way should be fine. What you're trying to do here is get rid of any orange peel before you compound/wax to finish. Keep the paper wet, I did mine in the kitchen sink. Every so often stop, dry the spot and see how you're progressing. You instantly see where orange peel still exist as the areas around it will have a slight haze. Do this until it's gone.
After you're done wet sanding you'll notice your work has a slight haze, don't panic this is normal. This is where the compound and wax come in. Start with the compound. I did 2 decent hand buffing jobs using the compound, wiped it off and you can see it'll start getting its shine back. Then I finished it all off with a couple coats of wax to get a good finished.
Viola, you're done. I used my phone so the pics don't show the finish very well so I don't have a good before/after wetsand/compound/wax pics to compar to.
Now go stick them on your truck and admire your work.
I'm quite happy with how they came out for a spur of the moment project. They look good and match great. For those afraid of doing this with rattlecans beware that proper prep work and patience is key. Most people would have a really hard time distinguishing my work from a professional paint shop doing them. Overall difficulty I'd say is about a 5. As long as you have time and a little common sense this should be extremely easy.