6 hours? Wow - that's so long... chances are it will become very, very tough!
If you have a digital thermometer, please check your oven temp and get it stable before you start. A mate tried to do it without and had some rather lovely bovine charcoal at the end of his effort. Oh well.
At 70 - 75C, four hours to five hours will yield a good quality with a little residual moisture in the meat. If you can get it to 80C and hold for an hour or so then there is some positive antimicrobial outcome from that - but dont' forget to wind back to 70C-ish for the remainder of the process.
Have a squiz over here:
http://yeastygoodness.blogspot.com/2009/03...sian-style.html - I documented one of the earlier batches.
I used Merc's recipe as the basis for that batch. However, I've found that long marination is not necessary. If anything, it only enhances the uptake of the salt in the soy / kecap manis / etc. Yes, salting firms and tenderises but without a washing stage it just makes meat too salty.
In developing a faster turnaround coating (because it sure isn't a marinade!), I went for kecap manis, chilli powder, fresh garlic very finely minced (to suit personal taste), peanut butter (not too much else it tastes too strongly of peanuts for a couple of days until it matures), 2 - 3 tbsp tamarind paste, your preferred kind of chilli paste (sambal oelek or lao gan ma chilli oil), dried chilli flakes, Szechuan pepper pounded with salt / pepper... Choose the flavour that best suits your palate.
Lotsa luck!
Cheers - Fermented.