Getting my webcam to work on Linux 2.6.31

1. # udevadm monitor
2. Plug webcam into USB port
3. See the following from udevadm:
   
KERNEL[1258313701.178493] add /kernel/uids/1006 (uids)
UDEV [1258313701.178517] add /kernel/uids/1006 (uids)
KERNEL[1258313701.829976] add /devices/pci0000:00/0000:00:02.0/usb2/2-4 (usb)
UDEV [1258313701.831655] add /devices/pci0000:00/0000:00:02.0/usb2/2-4 (usb)
KERNEL[1258313701.833268] add /devices/pci0000:00/0000:00:02.0/usb2/2-4/2-4:1.0 (usb)
UDEV [1258313701.834303] add /devices/pci0000:00/0000:00:02.0/usb2/2-4/2-4:1.0 (usb)

4. # udevadm info --query=all --attribute-walk --path /devices/pci0000:00/0000:00:02.0/usb2/2-4
   
   looking at device '/devices/pci0000:00/0000:00:02.0/usb2/2-4':

   ATTR{idVendor}=="046d"
   ATTR{idProduct}=="092f"

   ATTR{manufacturer}==" "
   ATTR{product}=="Camera"

   looking at parent device '/devices/pci0000:00/0000:00:02.0/usb2':

   looking at parent device '/devices/pci0000:00/0000:00:02.0':

   looking at parent device '/devices/pci0000:00':
   KERNELS=="pci0000:00"
   SUBSYSTEMS==""
   DRIVERS==""
   

5. Google 046d:092f and find out it's a Logitech QuickCam Express. Google some more and discover its driver is GSPCA, which is no longer a separate module but an in-kernel one.
6. # cd /usr/src/linux && make menuconfig
   Enable:
   Device Drivers -> Multimedia Support -> Video For Linux
   Device Drivers -> Multimedia Support -> Video capture adapters -> V4L USB Devices -> GSPCA based webcams -> Enable all SPCA5xx camera drivers. (Once the camera worked I found out by using lsmod that only SPCA561 was needed)
7. modprobe the new modules or reboot the computer
8. # udevadm monitor
   After plugging in the camera:
   
KERNEL[1258315384.769022] add /devices/pci0000:00/0000:00:02.0/usb2/2-3 (usb)
UDEV [1258315384.770643] add /devices/pci0000:00/0000:00:02.0/usb2/2-3 (usb)
KERNEL[1258315384.771997] add /devices/pci0000:00/0000:00:02.0/usb2/2-3/2-3:1.0 (usb)
KERNEL[1258315384.810075] add /module/gspca_main (module)
UDEV [1258315384.810481] add /module/gspca_main (module)
KERNEL[1258315384.821031] add /module/gspca_spca561 (module)
UDEV [1258315384.821191] add /module/gspca_spca561 (module)
KERNEL[1258315384.993956] add /devices/pci0000:00/0000:00:02.0/usb2/2-3/2-3:1.0/video4linux/video0 (video4linux)
KERNEL[1258315384.994056] add /bus/usb/drivers/spca561 (drivers)
UDEV [1258315384.994171] add /bus/usb/drivers/spca561 (drivers)
UDEV [1258315384.994277] add /devices/pci0000:00/0000:00:02.0/usb2/2-3/2-3:1.0 (usb)
UDEV [1258315385.011577] add /devices/pci0000:00/0000:00:02.0/usb2/2-3/2-3:1.0/video4linux/video0 (video4linux)

9. $ camorama
   The LED on the camera blinked and camorama reported "Cannot capture"
10. Google gspca_spca561 and come across http://lists.zerezo.com/video4linux/msg24804.html
11. # emerge -avt libv4l
12. $ LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so camorama

And then it worked, yay.

Note: all commands starting with # are run by root, with $ are run by my own user.