Exclude Pagefile on unmanaged SEP client

Hi.  On an unmanaged SEP12 client I need to exclude the Pagefile.sys file from being scanned by autoprotect.  However when I try to do so, even though the file is visible in explorer, I get an error "File does not exist".  Is there a way round this, or do I even need to do it - will the client exclude pagefiles automatically?