The only way I know of to change the multiplier is by connecting the L1 bridges using a pencil, rear window defrost repair kit or conductive pen (of course if it came unlocked then you don't have to do anything).
Nothing I've read has ever said there was another way. If anyone else has read anything different let me know, but I've gone to many sites and not one mentioned anything other then connecting the L1 bridges. Its not that difficult if thats your concern
unlocking the CPU and changing the multiplier are two entirely different things.
No motherboard can unlock a Duron or Tbird on it's own, as said above, the L1 bridges have to be connected with a pencil or condictive paint pen or other condictive implement. If your CPU is locked (as most are when they come straight from the factory) no amount of jumpers, dip switches, bios settings, or banging your head on you case will unlock it.
Once you have unlocked your CPU, if your motherboard has dips, jumpers or bios settings to switch the CPU parameters (FSB, multiplier, voltage)
you SHOULD be able to manipulate these to overclock. Motherboards that can manipulate these parameters:
Abit KT7 and its various iterations
Asus A7V and iterations
MSI K7T Pro 2A
Other boards may be able to change settings but none that I have heard of.