I did not post the topic, but recently saw on a discussion forum (don't know which one, I was searching for landscape mode, too), and there was mention of a small infrared keyboard from Pocketop. There is a driver for the keyboard that switches it to landscape mode.
Here is the link.
Install the driver for the Axim, then do a soft reset. Down in the corner where you choose the writing method, tap, and pick the keyboard from your choices. A small menu will then appear at the bottom. Tapping one of the icons will bring up a dialog that lets you change to landscape. It will then soft reset and be in landscape. You have to do a soft reset each time you switch.
I tried it and it seems to work, that is, it didn't crash. I haven't tested it thoroughly, but it seemed I couldn't get menus in some apps to work. I was able to read some Word docs etc. I use Snoopsoft Dashboard and the graphics for that program don't re-scale to the new resolution. But I think they are hard-set dimensionally as graphics.
You can give it a try and if it works, it will be a nice, simple cost effective (free!) landscape mode tool.