Sure you can! Get a copy of Fitted Knits by Stephanie Japel - she has lots of beautiful designs and has info an resizing that you could use for re-designing. Also, find a local LYS that has friendly and helpful creative types that will help you along the way - or grab KH buddy to take a look.
I've found the top-down method to making sweaters to allow for such design freedom (as you can see in the Fitted Knits book)
Good luck and happy knitting!