I got annoyed with Eclipse and not being able to easily figure out how to make project templates. So I decided to try and see if I could use XCode (v1.5) to develop midlets on Mac OS X.
The answer is yes and so I created a project template for midlets that is a decent starting place.

04/14/2006 - - This template will also work for xcode 2.2.1. - Also modified this so that preverify references match the actual location of preverify in the current mpp distribution.

to try it out you'll need the mpowerplayer sdk/emulator.

after you download the project template archive you will need to uncompress it and then put the "Ant-based MIDlet Jar" folder into 

/Library/Application%20Support/Apple/Developer%20Tools/Project%20Templates/Java/

or one of the other folders inside the "Project Templates" folder.

to use it, select "File -> New Project" and then choose "Ant-based MIDlet JAR" from the list of templates. You will have a project that you can build and run in the emulator to start from.

From the template description:

This project builds a J2ME MIDlet as a JAR file. Be sure to name the project a name without spaces in it; this name becomes the mainclass name and the name of the .jad/.jar file.

Note: you will need to either put the mpp-sdk folder into /Developer/Java/ or create a symbolic link (not an alias) to it in /Developer/Java/ (this is used to launch mpowerplayer and for the ant build file to find the sdk). To create a softlink use the following in the terminal replacing "/foo/mypath/to/where/i/put/mpp-sdk" with the appropriate thing on your machine:

 ln -s  /foo/mypath/to/where/i/put/mpp-sdk mpp-sdk

Alternatively, you can edit the project Executable arguments section and the build.xml file to have the real path to your mpp. but the symbolic link is easier.
Note 2: for OTA to work you'll have to update the MIDlet-Jar-Size: line in the .jad file it has to match the .jar file size or some (all?) phones will refuse to download it.
Note 3: For some reason the icon is not working on my phone (YMMV)

Here is the template archive to download.

questions or suggestions - post on the mpowerplayer developer forum.