The only way I know is using a tool like Melodyne or even the pitch shift in Peak (which isn't being made) I just tried to make an apple loop out of a 4 bar part, then use the transpose function in the sample edit and got 4 bars of static (YEA!).
I may have forgotten exactly what I used to do, BUT I could make an apple loop, then assign a ket to it (all in the apple loop editor) and then change the key in the track inspector. BUT it doesn't seem to want to do this now... Love when they change something and make Logic work a little LESS better than it was.
You can do that very easy on the fly using the Logic plugin "Vocal Transformer". It has a "harmonic" compensation parameter so you can achieve very native results. By the way 1-2 semitones is almost nothing for its capabilities.
If you want to lean some other Logic offline workarounds give me a sign, but I highly recommend the VT on the fly method.