As what you said, the “EnableEventFiring” is obsolete for sharepoint 2010. I don’t know if there is a way to enable it using PowerShell.
But Sharepoint 2010 has created a new property “EventFiringEnabled” to replace the “EnableEventFiring” method.
More information about “EventFiringEnabled”
Also here is an article about toggling events, I think it’s helpful to you.