Вот скрипт
Dim doc As Variant
Dim cell As Variant
doc = ThisComponent
cell = doc.getCurrentSelection
cellText = cell.getString
msgbox "->"+cellText
cellText = Replace(cellText,"П","М")
cellText = Replace(cellText,"р","е")
cellText = Replace(cellText,"и","д")
cellText = Replace(cellText,"в","в")
cellText = Replace(cellText,"е","э")
cellText = Replace(cellText,"т","д")
msgbox "->"+cellText
cell.SetString(cellText)
Меняет в активной ячейке буквы из "Привет" на "Медвед"
Подправьте и все :)