In my 3+ years of living in Oregon I've learned that you don't fight the rain. You welcome it, you embrace it, ya dance neeked in it. To challenge it is simply a losing battle.
It may just be best to bring extra undies, insulating layers, and gloves that you can change into after a couple of hours. Since the crowds are smaller these days, especially when it's raining, getting to and from your car shouldn't be an issue.
As for your goggles, you may try coating the surface with that stuff that makes water bead off.
I was on my way to Meadows yesterday, but turned back at Welches 'cause I could tell that it was going to be a bad (wet) day on the mountain.