[TxMt] How to add encodings to "Re-open with encoding" menu

[Boris Bliznioukov]

Hi All,

Is there a way to add other encodings to the "Re-open with encoding"  
menu? I only have Mac Roman, ISO-8859-1 and UTF8/UTF16 encodings in  
the list and I would like to add something like KOI8-R, CP-1251 etc.  
How can I do it?

Boris./