Need to replace dll in System32 with different version trusted ins

Hi,

I have read about WRP in Windows Vista but I still need to find a way to
replace
a version of ir50_32.dll which exists in C:\Windows\System32 folder with a
different version in order to run some products.

In Windows XP the installation setup takes care of this but in Windows Vista
this directory is a protected resource and only TrustedInstaller has full
control over the files. Hence, the file is not updated and simply skipped.

Is there a way of updating this protected file?

Also, when i try to register or unregister using regsvr32 the existing
ir50_32.dll file
I get an error messsage that registration has failed with error 0x8000ffff.
How can I find out whether ir50_32.dll is registered?

Thank you
N.