I haven't used the DM164140 yet, but I think you should be able to use your offline IDE as well.
In the
user guide section 2.2:
PROGRAMMING XPRESS BOARD USING MPLAB® XXpress Boards can be programmed using MPLAB X by following the same steps as described in Section 2.1 “Programming the MPLAB Xpress Evaluation Board” for MPLAB Xpress.
In addition to drag-and-drop, MPLAB X can run a post-build script to perform this action automatically. To set this up, right click on Project Name > Properties > Building and check the Execute this line after build. In the text box below it, type: cp ${ImagePath} Replace with the actual location where XPRESS board is mounted.
For example, on Windows, if the XPRESS board is mounted at D:\, the script would look like: cp ${ImagePath} D:\ For Mac OS X, if the XPRESS board is mounted at /Volumes/XPRESS, the script would look like: cp ${ImagePath} /Volumes/XPRESS
You could also develop offiline with MPLAB X IDE, then
package your project to a zip file. When you want to program your board with MPLAB Xpress, you could import your zipped project with MPLAB Xpress.