OK, here's an alternate way to do it:
Download the attached file and save it as OrcaView.xpi (the forum won't let me attach .xpi files)
Install the downloaded file into Orca (just drag and drop the file onto it)
Restart Orca as instructed
When restarted, go to Tools -> Mozilla Addons
Select Extensions -> OrcaView -> Options -> Install
You should get a successful confirmation dialog
Open Avant and go to Tools -> Avant Browser Options... -> Add-ons
Enable the context menus: Open Link Target in Orca and View This Page in Orca
Close the options dialog
You should now have the ability to right click a page or link and open it in Orca
Note: the script relies on Orca being installed to the default location of c:\Program Files\Orca Browser\
If it is installed elsewhere, edit the two orcaview*.html files located in:
%appdata%\Orca Profiles\.default\mozdata\UserData\extensions\{5D558C43-550F-4b12-84AB-0D8ABDA9F975}\
Also, the code is not mine (again). It is based on
FirefoxView by Alex Sirota.