MagicDraw RConverter is the tool to convert Rational Rose project (.mdl) to MagicDraw's readable file (.xml). You can download MagicDraw RConverter Evaluation version at http://www.nomagic.com in the download section.
To import Borland Together files you need to open XMI file with MagicDraw 9.5 version, save and then open with MagicDraw 10.0 or later version.
The MagicDraw 10.0 version or later does not have Export As Unisys XMI commands.
Unisys XMI is for UML 1.3, MagicDraw 10.0 or later uses UML2 metamodel.
There is a Visio plug-in that allows you to export to XMI 1.0. This format is supported by MagicDraw.
MagicDraw RSXConverter is an eclipse plugin deployed in an RSA/RSM environment for exporting an RSA/RSM file format (*.emx, .efx, .epx) to a MagicDraw readable file format (.mdxml). You can download an evaluation version of MagicDraw RSXConverter at http://www.nomagic.com in download section.