Excel to Gcode

Hi All,
I'm trying to work with excel to generate a toolpath for my 4th axis.
got a point file from rhino into excel then did the trig to find the z
axis position and A axis angle position from the original x and Y.
The problem is: when going past 180 degres the toolpath gets mirroed
on top of the other 180 deg.
I think I should out put the the degress from 0 to 360 but can't
find a formula to do that.I'm using a circle divided into 4 so the
angles changes from let'say; -65, 65....on every quadrant.
Have tryed to subtract 90 deg from the quadrante but it still gets
mirroed.
BTW: I need to cutout odd shape windows on a ovalshape tube.
Every high end cam software I've tryed don't want to follow a odd
shape line on top off surface when using the rotary axis, it only
wants to machine the Whole surface .Tryed mastercam, powermill, and
Vector,
any Ideas?