MrBayes has Mac release for PPC Mac. In order to get better performance without rosetta it is possible to compile MrBayes for Unix from source code, thanks to Mac OS X being a Unix system.
However, if you go into the folder and make, you will end up haveing error message. I read from a forum that you need to do the following:
Open the Makefile in a text editor and add the following line after line 32, i.e. after the check for architecture in relation to READLINE:
USEREADLINE = noSave the file and do
rm *.o
make
Good luck with your phylogenetic analysis!