Any way to do this in Scribus 1.4.6?
no
If Scribus can open a file of a certain type then it should be listed in the "Files of type" drop-down box in the Open dialog. If the type of file isn't listed then you can be fairly sure that it can't be opened.
This might be of some use: http://forums.scribus.net/index.php?topic=767.0
And here's the same question answered elsewhere: https://graphicdesign.stackexchange.com/questions/96032/export-from-indesign-for-scribus