Well, if you could power the thing up while partly assembled, the +5 and grounds will announce themselves to your voltmeter. Failing that, you could find any motherboard part like a 74xx series IC or microprocessor, or even the bypass caps, identify their +5 and gnd from a datasheet, and measure back over to the connected but powered down adaptor looking for as close to zero ohms as the resistance of your test leads and probes allows. After finding +5, ground return, and shield return ground on the adaptor, look for the low speed identifying pullup resistor 1.5K +-5% ohms to +5V on the downstream USB 1.1 PCMCIA adaptor side D- signal. The remaining signal is D+. From somewhere on the net I once downloaded the huge USB 2.0 spec, the 1.1 compatibility info is in figure 7-21 and of course the connector pinouts for std USB connectors are there also. [] ]'>

The needed additional software, if any, I leave to others more knowledgeable and determined...