好像还没见过帖子介绍这个，我来写一下我做的步骤。我用的手机是Google G1 and myTouch 3G on Android 2.1, 用的tmobile to go service. 两个手机步骤一样。
MGMaps 是一个Java J2ME的在线地图和导航软件，在android上跑需要做两件事：转java成android apk和装j2me runner.
1.下载MGMaps地址: http://wap.mgmaps.com/get.php?version=13&platform=main&submit=Download
2.到这里转成apk 文件：http://www.netmite.com/android/srv/2.0/getapk.php
3.把apk文件装到sdcard上。当你运行第一次时，它会提示你下载j2me runner.你可以在有wifi的地方下载并安装。
4.最后需要加"magic string"使之可以免费在tmo2go跑data:
"After installing the app, go to menu to change settings:
>settings
>advanced
>append to http requests:
>other:
tmobile=t-mobile
This appends the 'magic string' that allows tmo data to work.
Not everything works, but all the important stuff works. I know yahoo maps, and openstreetmaps work.
Traffic info works if you choose traffic.com as traffic info source.
Map search powered by google works also."
Credit: 抄自HowardForums.