When you're doing Half Cabs, you should have your 180s and your Fakies down pat. You shouldn't have any issues with either of those tricks. You really don't have to roll Fakie for a long distance to do a Half Cab.
What you want to do is, is you want to get into the position that you're rolling backwards. Unless you have a free coaster, your drivers going to engage your crank set backwards. So naturally, you're gonna have to pedal backwards. And as you arrive at the point that your dominant foot is forward, you're gonna wanna give it a really nice push forward so that it'll bring the front end up. What this is gonna do is, again you wanna start rotating with your head, the rest of the bike's gonna follow. As you crank forward, the front end's gonna come up and you wanna pop. As you pop it's basically you're doing a Bunny Hop in reverse, but you're gonna have to kinda crank into it.
As you crank into it everything's gonna pop up. You should already have your head going in the direction that you wanna spin. About 90 degrees you wanna spot your landing. Make sure your landing is in the direction you're traveling. As soon as the bike comes around and you get it level again, you wanna stop your rotation and kind of set the bike down evenly. Ride away clean.
And that's how you do a Half Cab.