You can work this out with a little reverse engineering. Take a default project and add the Win64 platform. Then save the .dproj file. Then change the values of both platform and config, and save another .dproj file. Then run these files through a difference program. The output looks like this:
8,9c8,9
< <Config Condition="'$(Config)'==''">Debug</Config>
< <Platform Condition="'$(Platform)'==''">Win32</Platform>
---
> <Config Condition="'$(Config)'==''">Release</Config>
> <Platform Condition="'$(Platform)'==''">Win64</Platform>
Now that you know where the values live, it's just a simple XML parsing task to extract them from the file.
Now for a rant. If anyone from Emba reads this, would it be possible to change the program to store the settings from the IDE in a different file? Perhaps named .dproj.local or .dproj. or similar. That would allow us to commit the .dproj file to revision control and not have it show up as modified every time we switch platforms for a debugging session.