This should do pretty close to what you want:
System Preferences: Keyboard & Mouse: Keyboard Shortcuts
Refer to the shortcut for "Keyboard Navigation: Focus on Dock"
By default, the shortcut is control-F3. Pressing that selects the last selected icon in the dock. Use the right and left arrows to select the different icons. Press enter to activate the selection, up or down to go through the item's menu, or esc (or cmd-.) to cancel.
Pretty nifty, huh?