First, (purely opinion) I do not think Icehouse games (at the Icehousegame.org wiki or elsewhere) should be copied to the Rabbits wiki:
1) It's very difficult/annoying to maintain synchronization.
2) It's the *Rabbits* wiki, and many Rabbits have nothing to do with pyramids.
That said, sure, link all you want: links are easy and rarely change and, if they do, will have redirects.
Second, you will have to request that the Origins site be added to the whitelist; otherwise, you have to "kill" the link to make it save (remove "http://"). THis will, of course, look ugly--it's a mere placeholder/reminder until the site is whitelisted by an admin.
Hope this helps;