RE: Making ski wear

The problem: One very round 6 year old daughter who is desperate to go on a
skiing holiday... but we cant find any readymade trousers/salopettes to fit
her.

Can anyone point me to web sites where I could get the
advice/patterns/materials necessary to make her some salopettes. I have no
experience whatsoever in making outdoor/waterproof wear..is it significantly
more demanding than making a basic pair of trousers?

Thanks
Karen