Direct-die is possible, but I haven't seen any DIY attempt that did it right. What you need is a Parylene-C coating on the CPU package, which both prevents erosion and is an impermeable dielectric sealant. But unfortunately price will be an obstacle: $500 for a batch of 4 wafers ( chips are normally coated before soldered to package ). See this thread before you attempt anything, more info on Parylene-C deposition:
http://forums.procooling.com/vbb/sho...8644#post68644