Try this:
1) In your TiddlyWiki, create a new tiddler named "download", containing:
```
\import $:/plugins/benwebber/dnd/ui/Buttons/export-player-edition
<$list filter="[{$:/info/url/search}match[?download]]">
<<actions>>
</$list>
```
2) tag this tiddler with `$:/tags/StartupAction/PostRender`
Then, to trigger the action from a URI, add `?download` to the end of the URI. The result should be the same as using the "Export Player Edition" button from the sidebar page controls.
Note that I tested this by loading into a browser. It might not work when using wget, as "$:/tags/StartupAction/PostRender" is only triggered when running in a browser. I also tried "$:/tags/StartupAction", which should work even without a browser (i.e., using wget), but it didn't seem to work for my tests, and I'm not sure why.
Let me know how it goes...