If he wants to enter a PrC early via skill prereqs, have him check out the Primary Contact feat, and its prereq Favored, in Cityscape. PC explicitly gives a skill rank above your normal maximum. Only to one skill, but still. Good for getting into, say, the 3.5 constructor PrC.
Skill Focus doesn't do that. If bonuses did that, a stat of 18 would let you get in 4 levels early.