Sorry if this have very little to do with Sims movies, but I couldn't find any better place to post.

I have tried exporting a mesh with earlier version of TSR Workshop. It was something like clicking export and then going to Milkshape and importing the file.

But how is it done now? I just can't figure it out ...

I figured it out myself:

1. Install MilkShape 3D 1.8.5
   
   
2. Install TSR Workshop
   
   
3. Now, you need to give Milkshape a few plugins so that it will understand the .wso format. You will need those files:
   

   msTSRWorkshopExport.dll
   msTSRWorkshopImport.dll

   
   They can be found in one of these directories:
   

   C:\Program Files(x86)\The Sims Resource\TSR Workshop\Extras\Milkshape Plugins
   C:\Program Files\The Sims Resource\TSR Workshop\Extras\Milkshape Plugins

   
   The files should be copied to one of these directories:
   

   C:\Program Files(x86)\Milkshape 3D
   C:\Program Files\Milkshape 3D

   
   
4. In TSR Workshop:
   Create whatever object you want to edit. Like, a shirt. Click on the Mesh tab, chose a low res or high res version on the pull-down menu, and click the export button at the right. save as myCoolShirt.wso
   
   
5. In milkshape:
   Import myCoolShirt.wso with File > Import > TSRW Object ...