00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
00:01.0 PCI bridge: Intel Corporation Mobile 915GM/PM Express PCI Express Root Port (rev 03)
00:1b.0 Audio device: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller (rev 03)
00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 1 (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 03)
00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 03)
00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 03)
00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 03)
00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d3)
00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 03)
00:1f.2 IDE interface: Intel Corporation 82801FBM (ICH6M) SATA Controller (rev 03)
00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 03)
01:00.0 VGA compatible controller: nVidia Corporation NV43 [GeForce Go 6600] (rev a2)
06:05.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5788 Gigabit Ethernet (rev 03)
06:07.0 Network controller: Intel Corporation PRO/Wireless 2915ABG Network Connection (rev 05)
06:09.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev b3)
06:09.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C552 IEEE 1394 Controller (rev 08)
06:09.2 Generic system peripheral [0805]: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 17)
06:09.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 08)
06:09.4 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev 03)

You can find out what keycode is generated if you press a key by using xev.

Content of $HOME/.Xmodmap

keycode 160 = XF86AudioMute
keycode 174 = XF86AudioLowerVolume
keycode 176 = XF86AudioRaiseVolume

Put this in your .xinitrc or some other script which is executed if X is started.

# load local modmap
test -r $HOME/.Xmodmap && xmodmap $HOME/.Xmodmap

Now all keys or keycombinations which produce a keycode of 160, 174 or 176 have gotten a keysym name.

There are several possibilities of assigning functionality to those keysyms, I am using xbindkeys.

Relevant lines of my configuration file ($HOME/.xbindkeysrc)

"amixer set PCM 1-"
XF86AudioLowerVolume
"amixer set PCM 1+"
XF86AudioRaiseVolume
"amixer set PCM toggle"
XF86AudioMute

Again put this in your .xinitrc or some other script which is executed if X is started.

xbindkeys &