Got it to run in Google Chrome without any problems. Thanks Predan.
I also was able to run the Pre calculator extracted from the WebosDoctor package (figured that it would not access the hardware) by copying Predan's 'frameworks' folder under the 'com.palm.app.calculator' folder at the same level as the 'app' folder, and editing index.html to change the line
<script src="/usr/palm/frameworks/mojo/mojo.
js" x-mojo-version="1" type="text/javascript"></script>
to
<script src="frameworks/mojo/mojo.
js" x-mojo-version="1" type="text/javascript"></script>
The calculator is fully functional, by the way.
It would be obviously better to have the frameworks folder at a higher level (with a corresponding change to the above amendment), so that it served all programs.
So it looks like we can do some work customising the supplied programs to operate more to our liking while we wait for the SDK.
I have attached an image showing the Pre running in Google Chrome on my monitor.