Haven't worked on that platform myself...  I'm assuming it should be no different than any other VM based deployment.

The release notes recommend using the VSOM Software Management page...

Release 7.6 and later—Use the Software Management page on the browser-based Operations
Manager to upgrade all of the servers in your deployment.

I would follow those directions, but I'm personally also likely to 'tail -f' the upgrade logs on the servers from an SSH session because I'm paranoid.

Wouldn't hurt to review the VSM 7.8 release notes yourself to be on the safe side.  I almost always force myself to review their contents as a matter of protocol whenever working on production systems.  Even if I'm really confident I remember it all.

Cheers and best of luck!