You will need a key chip to do the following. You can set the jackpot limit to something higher than $1,200 and then whatever the maximum allowed is (depends on game) will go to credits. Some games do not allow for more than $1,200 due to the W2G requirement, but some do. You will have to see if you can changed your jackpot limit to something higher than 1,200.
As far as "service credits," there's a product sold by Bettorslots called Bettor TITO. You can have that add-on configured so that if you push the service button, it will give you up to $100 in credits. The product will also allow the machine to accept it's own printed tickets (if you have a ticket printer).