To clarify:
You can download the Mobile version and it works without any further tweaking. Unfortunately, it's also a 30 day trial. You have to pay for it to keep using it.
You can also use the Mini version, which is a Java Mini Applet (MiniLet). That takes some additional setup before you try to run it. The instructions are in
this thread. Scroll down until you see "
1.2.1 Installing a MIDlet Manager". In order to install the .DLLs, you'll probably need a File Manager that will allow you to see them. I used Resco File Explorer to copy them to the /Windows folder.
Once you install the MIDLet Manager, you should be able to just click on the Opera Mini .JAD file and go from there. (I didn't follow the procedure on the Opera web site for installing to a phone. I downloaded the .JAR and .JAD files to my PC first and transferred them to my hx4700.)