Only ever done them from the front, only way as far as i can see.
Its a bit awkward on first few . what i do now is carry some coathanger wire which i tape the new cap to. this enables me to refit 13mm nut etc keeping cap in place with coathanger wire. the just pull the wire off breaking the tape.
20 minute job once you done a few.
Be careful as lots of brittle bits of plastic dotted around on these machines