I can't help you with the accounting, but I'll make a suggestion about the program. Build "crazy things" into your program. I mean two things:
1. The crazy almost unattainable award. For instance, you're a one-country airline, but you could offer a round-the-world first class award. I think they cost roughly $20,000 from Star Alliance or oneWorld. That's 1,200,000 points. You could bump it up, but I'd make it a nice round 1,000,000. (Find a nice round number in your currency.)
Will people redeem these that often? No, that's the point. You'll buy them when you need them. What you're doing is offering something to the super duper flyer. If I have 600,000 points on your airline, just flying your routes isn't exciting. But going anywhere I want in first class might get me to push.
2. Contests and prizes. Southwest is doing the Chief Reward Officer right now, which is well thought out. Priority Club hotels did the location finding contest last year (not the fastest quiz one, which got broken). Most people don't get that much - 500 points is a few $ - but you get good publicity. I'd make your top prize the Million Point award, for two.
At a lower level, offer super cool things. Send people to World Cup qualifiers in good seats. Send people to the Miss Universe pageant. Have backstage passes for a Shakira concert. Send people to Chicago for a week and put them in a nice hotel on the Magnificent Mile.
This won't cost you that much, but if you do a few a year, people will notice. Use your partners.
Also, let people buy these occasionally. SPG sometimes offers concert tickets. Auction off a few super prizes like World Cup / Miss Universe. You might even make money from the auction. Don't do this for ordinary merchandise like SkyMiles marketplace. Make it special.