I've posted IBM Java runtime enviroment for smartphone here once before and I'm sorry that one of the cabfiles were somewhat untested and didn't install properly. To solve the problem I've rewritten part of IBMs instructions for deploying the J9 runtime enviroment for windows smartphone.
If you have a device with WM2003Se, use the file posted earlier in this thread. If you have a device with WM5.0 I've included version 6.1 of J9 with this post.
Deploying J9 to Windows Mobile 5.0Use the following steps to deploy this WEME Runtime for Windows Mobile 5.0 CLDC 1.1/MIDP 2.0 on your target device.
1. Download J9 for your device:
� This means the file from the first post if you have a WM2003Se device
� This means the file from this post if you have a WM5.0 device
2. Unzip the archive to a temporary directory on your harddrive.
3. Create a directory called T9 on your device. (Ibm suggests the root folder, I prefer creating it in "\Storage Card\Program Files\")
4. Open the J9 folder and create a MIDP20 folder.
5. Copy the previously unzipped bin, lib and examples directories to the MIDP20 folder.
Note: These directories can be copied to any location you choose on the target file system; however, the \bin and \lib directories must remain intact. The base J9 executable and its shared objects must remain in the \bin directory.
You can make a shortcut to the emulator.exe file in the \bin directory. This is the main J9 file and it will install and run midlets.
I've also included a .reg file who will register .jad and .jar files wirh the emulator.exe in the \bin directory.
If you have NOT installed J9 in the \storage card\program files\J9\MIDP20\ directory you must replace this location with the actual location on your device in the J9.reg file
Hope this works better!

I followed your installation instructions (by the way, I'm trying to install Opera Mini in my Motorola Q), the problem that I have right now is that I can't import the Reg file that will associate JAD and JAR files with the Java install. How do I do it or where do I get a Register Editor that will allow me to import the Reg file?
Any advice will be a great help.