I've been using Kte v1.5 since I installed it back in the mIRC v6.x series, and it still works today with 7.46:
Code:
; Kte - Kamek's Theme Engine v1.5
; MTS-compatible theme engine (standard v1.0/1.1) -- homepage: http://www3.brinkster.com/ircweb/mts/
; Dialogs made using Dialog Studio

Code:
; K MTS Theme Editor v0.71
; by Kamek, for mIRC 5.91
; /kthm to open it
; dialog tables generated by Dialog Studio

; Features:
; · Schemes support
; · Events support, with descriptions
; · Colors support
; · Font support
; · Nicklist support, including custom characters support
; · Theme reorganizer (sorts theme items)
; Todo:
; · Add support for Images and Sounds
; · Make a better RGB selection method
; · Add preview
; · Add options
; · Add scheme management window (move/remove)

; New in 0.71 (27 sep 2001):
; · Added confirmation for saving when closing the theme editor
; · Automatic fix for Timestamp in MTS 1.0 to 1.1 conversion
; New in 0.7 (29 aug 2001):
; · Added support for unknown items (only raws and a few other for now)
; · Fixed few bugs
; · Changed the way the editor works (it doesn't add blank items anymore)
; · Added the reorganizer

Unfortunately, it appears that homepage is dead...