Huh, found a solution:
Enchaining multiple commands with & seems to work.
cmd /c cd .. & Server.Test\bin\Debug\ServerTest.exe
previous version
cmd /c cd ..
cmd /c Server.Test\bin\Debug\ServerTest.exe
didn't work as the console terminated after changing the directory, thus changing nothing.
I'd still be interested if it is possible to change the working directory for the pre/post build steps from codeblocks.
Cheers,
Koonschi