I'm having a problem using the CompetitiveUninstallWrapper

I've followed the instructions to use the wrapper, renamed the setup.exe to SEPsetup.exe and renamed the CompetCleanerSEPinstall.exe to setup.exe, put the CompetitiveUninstall folder in the deploy package etc.

When I deploy the CompetitiveUninstall works as expected, and then starts the SEPsetup, but then returns an error 1155:

The reason for the error is that the C:\TEMP\Ctl-Inst\ contents are all removed as soon as the SETsetup.exe is executed. Has anyone else had the same experience?

Sandeep Cheema's post here: http://news.support.veritas.com/connect/forums/deployment-endpoint-11-heterogeneous-environnment
seems to be a possible workaround, but it looks like this should be working from what i see in the readme

Any ideas?

Thanks,
Alan