The only solution I can think of is to use iframes to load the external pages. You would use the mojoPortal Html Content feature, in the FCKeditor you would click the "Source" button on the toolbar to go to html view. Add an iframe like this:
<iframe src="http://yourexternalpage.html" title="whatever" width="100%" height="600px"></iframe>
You may have to experiment with the height setting to get the results you want.
The only problem is if you have to login to the other apps it probably won't work unless the app is in the same domain, because the browser won't let you set a cookie for a different domain from inside an iframe (its a security feature of the browser).
Hope it helps,