I've done a polar alignment with my D5300, BYN and Sharpcap. It did work, but it was slow and clumsy compared to using the guidescope and its camera. One of those things that you do once, just to see if it you can make it work. :-)
My $0.02 - simpler and faster to just use the guidescope + sharpcap. Then once polar aligned, disconnect sharpcap and when ready for guiding, connect up PHD2.
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras: Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer: Thinkpad x230, Win7Pro/64