OK, I found the post:
But I think I've got a slightly different situation. I compile and such using NAnt, and inside of NAnt call NSIS to create my installer. I don't seem to fit the mold in the noted conversation because I have to reference the NSI file in the compile. So my command would look like this:
commandline='/V3 /OInstall.log /DOUT_FILE="D:\Program Files\MyApp\MyApp.exe" InstallMyApp.nsi'
This won't work because /D doesn't support spaces. I also can't make the /D the last argument because InstallMyApp.nsi has to be. Any help? Wouldn't it be easiest to allow quotes on the \D?