Translate the English [CustomMessages] from the installer (and any include files).

For example, the default (English) strings:

; Misc
rsDefault=Default
rsLanguage=Language
rsDestinationLocation=Destination Location
rsXIsRequired=%s is required.

Translated strings:

; Misc
Korean.rsDefault=초기화
Korean.rsLanguage=언어
Korean.rsDestinationLocation=목적 위치
Korean.rsXIsRequired=%s is required.