P-rench, I got this working in Lucid and Karmic by simply adding
<Video>
<CaptureHeight>480</CaptureHeight>
<CaptureWidth>640</CaptureWidth>
</Video>
as you did in config.xml, between the <Lib> braces, no other editing seemed necessary.(in Karmic, there was a already a <Video> section, not so in my xml for Lucid)
Also, the Sigma Micro (1c4f:3002) that I bought off ebay has an inbuilt microphone, as well as led lights, which I presume is for additional lighting. I bought it for a similar incredible price.