Paint it black. Clear it. Paint chrome over it. Clear again. Done.
Looks okay-ish. Doesn't really like temperature.
Normal car paint works better.
I've seen real chromed valve covers, but that's really expensive.
I polished one myself once, but the material doesn't really lend itself well to it. After 6 hours of buffing it still looked a little cloudy.
You can polish it.... your self as stated. . . I have done a few. . . .you have to keep after it. . . . .everytime you wash your car just clean it up with some polish and it will stay nice. . . .. DONT PAINT IT CHROME that looks like crap.. . . .paint it black or red or blue or what ever color your car is but DO not paint it chrome. . .
I have a friend who powdercoats. . who could do a nice metallic color on it. .. let me know. . .i can arrange it for you . . . or look for a local powdercoater. . .. or i will have alot of free timeon my hands for the next 3 months. . . .so if you want to send it to me i can polish it for you for a small fee. . .