I have always had a skinny tall child..here are the tips from the Aust prem site:
use a belt with pants (you can get little belts from kids stores)
buy waist adjustable pants (like already mentioned)
buy a size 00 and use as shorts (felix does)
I found some braces in an ops shop..a bit daggy but possible pants holder upers 9haven't tested yet)
I buy bonds stretchy t-shirts becausethey are long and leean rather than the majority of baby t-shirts with are for short and fatties..
Felix has exactly the same proble with the bonds stuff Melinda! If he want a cloth baby then we'd be in huge trouble..

Oh that's my tip..put your baby in cloth heaps make fatter bums..

Glad we aren't the only ones!