Pick up a copy of the "Timber Frame Joinery & Design Workbook" from our online store: http://st1.yahoo.com/tfguild/deswor.html
there are a couple very good articles in there describing the angles you are looking for,

or

use a good CAD 3D Modelor, (Modeler, Modellor?)

or

hire a timber frame designer (like me),

or

review "Hip and Valley Framing" and the Hawkindales on this web site at http://www.tfguild.org/tool2.html, which includes a downloadable spreadsheet for automation of your calculations.