Use the Bcdedit command-line tool to enable test signing. To use BCDedit, the user must be a member of the Administrators group on the system and run the command from an elevated command prompt. An elevated command prompt can be launched by creating a desktop shortcut to cmd.exe, and then using right-click and "Run as administrator."
The following shows an example of running BDCedit at the command prompt:
// Accept test signed kernel mode signatures
Bcdedit.exe –set
Bcdedit.exe –set TESTSIGNING OFF
The TESTSIGNING
boot configuration option determines whether Windows Vista accepts test signed kernel mode binaries. The option is not defined by default which means digital signatures on test signed kernel mode drivers will not verify and will not load. When Windows Vista accepts test signed kernel mode binaries, some premium content that is protected may not be accessible on the system.
ref :
http://msdn.microsoft.com/en-us/library/bb530195.aspx