How to get microphone working on dell d630?

[Michael Yang <michael.yxf@gmail.com>]

ALL:

I have debian lenny/sid on my D630 laptop. The sound driver has been 
setup properly with alsa and is working well.However,  the 
microphone(external, or built-in) doesn't work at all.

I use skype software quite a lot, so it's very important to me that I'd 
like to know how to get it working. I searched on the google, but didn't 
get an answer. It seems to be an unresolved issue for D630. I'm 
wondering if there is anyone got it working before.
Is there a lead I can follow to set it up?

It's really appreciated of your helps.

Thanks.
Michael.