Hi Gordon,
It is not recommended to use soldered wires as a substitute to medical electrodes although it may work but it could pick up a lot of noise in the environment since the most common source of noises will be the electrodes and the wires you have at the inputs.The wires would be better if it is twisted or those that are shielded. Yes, you can use a scope to read the output of the board. I suggest that if you can't get an electrodes, you must check where does the noise is really coming from. A good starting point will be by grounding the input and observe if the noise goes away. If not, you must check your connection and wiring and probably find a better electrodes. The output when you attached the electrodes to human subjects body should look like a typical QRS complex.
Regards,
Phillip