Yes, you should be able to run the MSP from the command line and even pass it the /qb switch without it failing. The correct command line can contain the MSI file as well, although it's optional. See the following examples:
msiexec /p msipatch.msp /qb
msiexec /i A:\Example.msi PATCH=msipatch.msp;msipatch2.msp /qb
msiexec /update msipatch.msp /qb
Note: if Windows does not have the MSI package already installed, then the update can fail if it doesn't include the MSI file.