If you have version 1.13+, you can copy it in, and use berrybrew register to register it. If you don't have that version, copy the directory, then edit the data/perls_custom.json file in the berrybrew installation directory, and make it look something like (where ver: is the actual version number as downloaded):

[
  {
    "name": "whatever_you_want",
    "url": "",
    "file": "",
    "csum": "",
    "ver": "5.22.3"
  }
]
[download]

If you have existing custom perls, then that needs to be appended to the others. This new version will then be considered a legit "custom" version.