The answer to this is simply no.
Unless you want to swap in a manual transmission (i.e. AX-15), your choices are limited. The AW4 swap is a possibility, but it has many drawbacks as Blaine has pointed out before. You could swap in a 32RH from an earlier model TJ as well.
Unfortunately you can't install a transmission such as the GM 4L60E for instance. It's computer controlled just like the 42RLE, and the Jeep PCM has no way of talking to it and telling it when to shift, etc.
To be honest, I can live with the 42RLE, it's not the end of the world. Sure, the OD hunting gets annoying, but if you were mostly using it off-road or for trail use, then it would be a moot point.
It's only around town and on the highway that that OD thing really started to bother me.