Mach 3 is control software, repetier can do the same for free as well as just using the LCD. The firmware, I am sure smoothieware has 6 axis support. fusion 360 costs $1500/year to enable 5th axis support.
Pocket NC is $4k and comes with 1 year of fusion 4″x5″x3.5″ workspace. http://www.pocketnc.com/pocketnc/pocket-nc
5axismaker is at least $1k more than that and has a xyz with 2 rotary axis on the end, the way that you would have to do it with the MPCNC. Same deal on the software +needs mach 3.
It isn’t that it can’t be done but the cost of the software that is limiting it. $500 for a cnc and 3x’s that for the software/year is a bummer.
Why not just flip your part? If you make jigs/fixtures (on the cnc) you can easily do angles as well. Theoretically you can flip it to any angle and achieve extremely similar results.