Download the 1.3 extensions to your C:/ drive from here:
Start the msi from an elevated command prompt - that is, right click Command Prompt icon in Start menu and select 'Run as Administrator'. Issue this command:
C:\msiexec /i VSeWSSv13_x86_Build_307_CTP.msi
This will prevent the UAC from causing the VSeWSS 1.3 to "fail prematurely".
sn.exe meant for 32-bit OS runs without error on 64-bit OS and incorrectly shows message indicating success.
Latest release is a .exe file, so this shouldn't cause problems.