Via excavation closeup
I wanted access to the CE1 signal coming from the CPU, separated from the RAM's CE1 input. Normally I'd just cut the trace and solder one wire to each side of the cut.
But here, the trace was on an internal layer. As it turns out, it was on the fourth layer from the top. I used a really sharp knife to excavate a hole in the top few layers (all power/ground polygon fills) to get access to the internal layer.
The internal trace is really tiny and fragile, so I had to use very tiny wire to connect it. This is a single strand from some 26 AWG stranded hookup wire.
For mechanical stability, I made some cuts in the top layer's ground fill to give myself some makeshift 'pads' to attach the tiny wires to.