You could also try using BlankWorks from FTI (www.forming.com). It is an add-in that will flatten anything including imported data and complex (formed) geometry.
Derek
I had to jump in on this one with a bit of shameless self-promotion (at least for the company I work for).
Forming Technologies Inc. (www.forming.com) makes an add-on product for SolidWorks called BlankWorks that will develop very accurate flat patterns for complex shapes that would require...