Rosscrazyelk,
You really need to leave that skull in heated water with dawn dishwashing soap for at least 2 weeks. 100-110 degrees in a 5 gallon bucket with 1/4 cup of Dawn Dishwashing (don't use the knockoff brands!). The bones will become saturated and soft and let the grease loose. Take it out and let it soak in Acetone for about 12 hours. Rinse and then put in peroxide. I use the 60% stuff. Most of the ones you buy in the store are 1-3%, but if you can get to a beauty supply company and get the 20-35% peroxide, that will work. When your there (beauty supply shop), buy whitening powder that they use to whiten hair. Let the skull soak in the peroxide for about 12-24 hours, after that it starts to really eat away some of the finer details of the skull, unless you already damaged/removed the nasal bones. Take it out, rinse and mix the peroxide with the hair whitening powder and USE GLOVES!! Mix 1:1 and coat the whole skull with the past liberally. Allow at least 5 hours to sit, rinse with hot water and put either in the sun (yes, I know we live in Washington State) or a high watt lamp and let dry. It will take about 2 days to fully whiten. Let me know if you have any questions and best of luck!!
Joel- BRT