I control my EQ6 in the way you're looking to do it.
I have a shoestring usb cable from the mount to the computer and I'm running EQMOD to control the mount.
You can also connect to the mount through the SynScan controller with the supplied serial cable and a usb adapter, just make sure you choose "PC Direct" mode on the hand controller.
I then run StellariumScope which connects to EQMOD and acts as a telescope in Stellarium. I then control the mount pointing with Stellarium.
As for guiding (I'm not sure about Metaguide) I used to use a QHY5L-II with PHD. PHD guides with pulse guiding through EQMOD by selecting ASCOM mount when you connect.
When I say it guides through EQMOD I mean that EQMOD issues all the commands to the mount for both pointing and guiding and PHD communicates only with EQMOD and not the mount directly.
This setup works really well and you can also use Astrotortilla for plate solving so you never have to star align again