Because Scribus can't import DOCX files you could always install OpenOffice/LibreOffice, open the DOCX file in that, then save the file as an ODT, then import that into Scribus.
It's an extra step but once you've got things set-up each document won't take much more than around a minute to process including opening/closing the application - i.e. Open OO/LO; open document; save as; Close OO/LO. (And it'll be quicker if you convert them in batches.)
You might also like to look at this post
http://forums.scribus.net/index.php/topic,742.0.html which talks about linking styles in ODT files to Scribus styles. It might make importing things a bit quicker if things are set-up the right way.
Having said all that, if you are not in the position to install software on your computer - and many aren't - you might want to look at an online DOC -> ODT converter. There are many available but I couldn't personally recommend any because I don't use them.