It is possible to emulate powerpc but it would be pointless. PowerUp/WarpUp software is relevant only to BPCC/CSPPC and A1/Red1/Pegasos/Efika users because there old PPC native PowerUp/WarpUp software will run faster than 68k native.
But in WinUAE PPC native software wont run faster than 68k native. Probably opposite since writing PPC JIT for handful of (broken) PPC titles is overkill.