Can LED's be used as turn signal bulbs without modification? I'm not good at wiring and all that jazz but I'd like some nice crisp LED's to go with my HID's if possible. Here are a few I found, will they work?

3457 Hyper White LED Bulb: eBay Motors (item 170508198914 end time Aug-01-10 12:39:22 PDT)

2x 3157 3156 WHITE 24-LED Turn Brake Car Light Bulbs: eBay Motors (item 120535905900 end time Aug-24-10 01:56:14 PDT)

Or any other suggested bulbs would be great!