I'd just get a straight pattern to work from. Most sweater patterns are knit straight, so you shouldn't have a hard time finding a good pattern.
If there's a particular stitch pattern you want to incorporate, let us know, and we can help you translate it from circular to straight needles.
Hope that helps,
KnittingHelp Queen Bee
"Don't ask yourself what the world needs. Ask yourself what makes you come alive and then go do that. Because what the world needs is people who have come alive." Howard Thurman