While we don't have that exact feature, there is an easy workaround you can use. When you are in the Sheet Set Manager, there is an option on the drop down menu to convert your DST data to a DSD file that can be used with ShareNow.
See the attached screen shot.
The steps are:
1) Select the desired sheets in the Sheet Set Manager. You can select the root node to use all sheets, or use CTRL-Click to multi-select specific sheets.
2) In the Sheet Set Manager toolbar, click the drop-down arrow next to the middle toolbar icon.
3) Select the "Publish Dialog Box..." option. This will take your selected DST sheets and create an unsaved DSD file and open the Publish dialog box with that DSD data.
4) In the publish dialog box, save the list of sheets to a DSD file.
5) Use ShareNow to publish your DSD to Freewheel.