I have a number of CON1's, CHAM1, CHAM44. My experience however is only with the S+ and PE+ (Video Poker)
On a S+ there is a 4 pin interface on the motherboard that connects to the CON1.
Only 3 of the 4 pins are active (schmatic shows PIN4 as unused) and only 2 connect to the CON1 as the CON1 did not directly support the Data pin.
The 3 pins are Coin IN, GND, Data.
Coin IN & GND - momentarily short when a coin is inserted to the S+ (or a credit is played) this momentary short causes the progressive to increment.
When the top pay is hit (progressive) a longer short occurs and it triggers the Con1 to go into jackpot mode.
Looking at this Cham1 board I suspect that the J2 interface with 3 pins might be the connection to the machine.
Since you are already working with the board with PSP you should be able to take a small wire and jump pin 1 & 2 and by quickly shorting them prove if this increments your progressive.
The Data wire is used when you have a CHAM2+ connecting to the S+ - It displays the jackpot amount on the Coin in / Winner paid windows on a Top Award.
I am not sure if the Cham1 would support the data pin or not as it pre-dates the ChamII.
As I already mentioned the CON1 did not have a data out. You could however use a Mikon Gateway (another board) that connects to the display out of the CON1 and the GND from the 3 wire interface to create the data out pin and then it would display the amount. This is also what you need to use as well on a PE+ (Video Poker) to display the jackpot amount on the screen instead of the word progressive.
To correct an earlier post the CON2i (Mikohn Supercontroller) only worked with ChamII (Non plus) and did not work with Cham1 boards.
Con1 --> Cham1
Con2 --> Cham2
Once you figure out the pins to make it increment this would connect to your S2000 the same as a Cham2 board would.