There's not much to it, however I wouldn't advise it. The disadvantages far out weight the advantages. The oil injection is a very reliable system because it uses the oil it's pumping for lubrication. I have never seen one fail except for lack of maintenance. O.K. I'm getting off my soapbox now.
If you want to go to premix you will need to remove the oil pump, on your ski it's under the carbs. you can either remove the drive gear and put the pump back on or get a block off plate. Block off the oil line to the pump, plug the two injector nipples. You will need to leave the oil tank in the ski to drip feed the rotary gear. You can get an oil block off kit from SBT.
After you remove the system you will need to mix approximately 3oz. of API-TC synthetic oil with every gallon of gas, SDB can give you the exact amount.
Lou