how to block certain file extension download (i.e. pwdump7.exe, lsahook.dll)

Hello,

I run WebSense Security 7.8.4.

I don't want to block all file extensions since they are allowed at the moment, but how can I block certain .exes, dlls, etc.

I read on File Blocking and File Type and it talks about blocking extensions, but I only want to block certain exe and not all exe (i.e. pwdump7.exe, lsahook.dll) from download. Not sure if this is possible or not? If I it is, can someone point me in the right direction?

Thanks in Advance,

Joey