Well, the only way you're going to get the Url Master module to handle it is if you can get the correct website (the one with the new url) to respond to the old urls. To do that you'd have to point the reckon.com.au domain at the reckonlimited.com.au site, which I assume you can't do because you've already created the new reckon.com.au site.
If you have already created the new reckon.com.au site, and it's got the Url Master module installed, you may be able to still redirect them.
Here's what you would do:
1. Create two new tabs, one for each of the to-be-redirected urls. As you don't want them to be visible from the menu, exclude them from the menu via the page settings. Customers won't see these urls unless they're using an old link or search engine reference.
2. Put in the Url to redirect to in the 'external url' field
3. Create custom Urls for those new pages in the 'Page Urls' page. These will look like /pagename/tabid/xx/default - note, no .aspx on the end. Set the http status to '200'.
4. Go to the friendly url settings page, expand the 'advanced rewriting section', and select the option which says to 301 redirect to external urls.
Save all the change and try it out. What should happen is that your request the /pagename/tabid/xx/default.aspx page, which will then load up the page you created. However, the Url Master module will detect that you have selected to do a redirect to the external page, and will forward on the request, which will go to the reckonlimited.com.au version as desired.
Give it a try and see how it goes.