Two suggestions, though I do not have a specific solution to your question.
1) If it is plug & play ready as you believe, take a look at the circuit board and compare it against DCC replacement boards at the various manufacturers web sites as each decoder usually has a picture and the dimensions listed.
2) If the current circuit board has a DCC plug, you may be able to find a Z or N scale decoder to fit following the same procedure as described above.
If you have other Life-Like models with decoders, I would start there for possible answers to your question. Most manufacturers reuse the same control boards as a means to control costs.
Happy hunting!
Train Rascal