You'll still need to slacken the handbrake cables behind the handbrake lever to reset the handbrake mechanism in the caliper after the new pads have been fitted.
You don't need to remove any of the rear tunnel. Remove the flap in the carpet behind the tunnel, then use a small ratchet with a deep 10mm socket.
Correct procedure for replacing rear pads:
1) Loosen the handbrake cable adjustment nuts behind the handbrake lever.
2) Disconnect the handbrake cables from the calipers.
3) Retract the caliper pistons *, ensuring that the 2 cutouts in the face of each piston are horizontal.
4) Fit the new pads.
5) Refit the cables to the calipers.
6) With the engine running, press the brake pedal several times.
7) Adjust the cables so that both wheels are locked with 5 clicks of the handbrake lever ratchet.
* To retract the caliper piston, it needs to be turned and pressed in at the same time. The left piston should be turned anti-clockwise, the right one clockwise. Special tools are available to do it, or you could improvise. The pistons may be very tight to retract. If you remove the disc, then refit the caliper, the caliper will be held solid while you retract the piston.
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