Is it possible to deploy VMs using a template yet altering the specifications like additional RAM, CPUs and drives all using one command line?

I currently have to build VMs using our template, wait until it finishes building and then customize network settings, select customization specification file, RAM, CPUs and drives before powering it up.

I would love to script our unique custom builds with PowerCLI using one command line.  I guess I want to be able to over-ride some elements of the template while still using the OS.

We're running ESXi 5.0

Thanks in advance.