I set the BinRootFolder in the "Task queue to execute" register in the Generate... dialog. In the task "SD.Tasks.SelfServicing.VsNetProjectFileCreator" I set the binrootfolder property. 
my directory tree is as follow:
- 
parentDir
- Debug
- 
LLBLProject
- (bin\Debug)
- (bin\Release)
- llbl.csproj
 
- Release
- subdir1
- subdir2
 
I'd like to set the output path to Debug/Relase directory, so bin root folder should be set to parentDir. I tested with binrootfolder values like "..\" and "..."
Because this doesn't succeed, I tested an "easier" way... Creating a subfolder "test" in LLBLProject and set binrootfolder to "test\"... nothing changed. OutputPath in Visual Studio stays on the default (bin\Debug or bin\Release)...