2000 cherokee stereo wiring

I'm looking at a '92 right now, but I think this will still help.  From the engine compartment, look back behind the engine, closer to the driver's side.  Now look about 3-4 inches below the thick wire loom, and you should see a huge rubber grommet.  It's about 5 x 2.5 inches round.  You should have no problem entering there.  Slit an 'x' big enough to pass your wire through.  Fuse close to the battery, loom, and secure your wire away from anything that's moving.

For the bass blockers, I'm assuming your adding an amp, so you will probably have the deck removed anyway.  Simply wire them in behind the deck, and there's no need to pull the door panels.