A friend just had one of these specialists come to his house and do this. I guess the guy went through the house with a thermal imaging camera, and mapped out everything. Also looked at several months of utility bills and such.
And there's also a tax credit you can get if you make the necessary changes that the specialist lists. $1200 credit from MGE/KCPL if you make all the changes. I think the inspection was over $500 though...
http://www.energykares.com/
Info on getting the tax credit:
http://www.hpwes.net/