Talk to Dan Stern at http://danielsternlighting.com/. He should be able to help you out.

I have a set of jaune selectif H4 bulb capsules that I use in inclement weather. They are simply unbelievable in rain and snow. No glare at all, and they look really cool, too. They do filter out about 10% of the bulb's output, but it isn't really noticeable if you put them in front of 90/100W bulbs.

As for legality, it varies by state. They're legal here in Illinois in wet conditions. Not legal at all in Missouri if you're going to exceed 20mph. Legal all the time in West Virginia and Ontario. I'm always getting pulled over with them, though, so I keep a printout of the relevant state statute in the glovebox - no problems.

Hope this helps,
Tom
'82 300D 317k
'95 S320 138k
'96 Passat TDI 177k