I will be able to test my MM78 tomorrow along with the COP411 dumping, though unfortunately the 411 is an RC oscillator version so I will have to write some tricky code.
I got the dumper built. You can use a pot to set the voltage on the test pin. it's got a very high input impedance and a 10K pot between ground/15V seems to work OK. if you have the L version I am not sure if it will work or what voltage it needs vs. these "normal" chips.
To put the COP411 into test mode I am using a PNP transistor to 5V and four diodes in series to drop around 2.4V or so, which should make it sit at 2.6V. The data sheet says 2.5-3V max to prevent damage so this should work fine.