Not sure what you mean exactly. The MK3870 is factory programmed (masked) and can't be altered in the field (to the best of my knowledge) so, yes, it can be read, but no it can't be programmed.
What you want to find are one of the piggy-back 3870s, read the one you want duplicated and then program a 2716 and put on the piggyback cpu. Reading the device takes cycling the TEST pin as I understand it - there is a process, but it is a bit long and involved and you probably need to make some hardware up to do it...and then write software to run the hardware. I only know it CAN be done, I haven't attempted to read one (yet).
John :-#)#