They don't specifically talk about that for templates, like the vampire. However, they do outline a system for turning a monster into a class. Their example is a minotaur class, which has eight levels, six for the six hit dice and two for the +2 level adjustment. You could take these rules and develop a vampire class, but it would take some fudging. Their system is for creatures with hit dice, one level per hit die with some dummy levels interspersed to account for level adjustments. But the vampire template doesn't give you any hit dice. So you'd have to spend five levels not getting HD, skills, or increases to saves/BAB. Note that once you take one level in a monster class, you cannot take any levels in other classes until you finish the progression.
