I'm sure someone with a hatchback has done this. What brand kit did you use? Does it vent fumes out of passenger area? How did you run the cables? Pictures would be great.
I used the Moroso blue box kit. It's the only kit I could find that was NHRA legal, since our cars don't have a rear firewall. It's a sealed box and vents fumes outside the car. I mounted mine in the sparewell in the trunk, and also mounted my master cutoff switch (required by NHRA when relocating a battery) to it. I'll take some pics when I get a chance if you like.
I'm running a Moroso Batt box as well. I'll include a pic below. It has a sealed cam-lock top and yes it does have a ventilation tube you plumb through the floor. You will also need a remote battery cut-off switch placed at the rear of the vehicle, in sight view (not hidden) as per NHRA rules.
This is where I put my cutoff switch. This is an example of where NOT to put it. I'm moving it to behind the license plate so I just have to remove the plate when I'm at the track. Remeber- the switch MUST be visable at the rear of the car to be NHRA legal. (i found out the hard way)