Determining conductance / capacitance and inductance per unit length
If the cable contains no magnetic material, then you can compute both L and C per unit length from the impedance and the speed of light in the cable.
If you have a long enough length of cable for the speed of your pulse generator an oscilloscope, short the cable far end and time the length of the pulse you get from putting in a step. This is twice the electrical length of the cable. Now terminate the far end, and see what value resistor completely removes the reflection. This is the impedance of the cable.
These measurements are likely to be no more accurate than looking up the cable type in a catalogue.