Intel designed the slot one Celerons to not be SMP capable. With this tricky mod, they will be. There is a finished Celeron on the bench and the newly finished one in the vice holder.
Because I tend to handle my hardware a lot, and the wire-wrap wire can be rather brittle, I taped it down.
A pin on the processor needs to be grounded (1), as well as a pin on the PCB (2). The wire crosses over to the other side, (3) and is attached to a landing on the reverse side.
The processor pin on the picture above needs to be disconnected from the PCB. This shot shows the connection drilled out to remove the connection.