Вот еще что нашел:
Код:

///////////////////////////////////////////////////////////////////////////////
// Find given text in given file, and replace
// complete textline with given text.
// Created: March 27, 2002 by S.T.I.Bracke
// Revised: May 22, 2002 by S.T.I.Bracke
function ReplaceLine(strFilename, strFind, strNewLine: String): Boolean;
var
strTemp : String;
iLineCounter : Integer;
a_strTextfile : TArrayOfString;
begin
{ Load textfile into string array }
LoadStringsFromFile(strFilename, a_strTextfile);
{ Search trough all textlines for given text }
// old line
// for iLineCounter := 1 to High(a_strTextfile) do
// new line corrected by Nikolaus Moll
for iLineCounter := 0 to GetArrayLength(a_strTextfile)-1 do
begin
{ Overwrite textline when text searched for is part of it }
if (Pos(strFind, a_strTextfile[iLineCounter]) > 0) then
a_strTextfile[iLineCounter] := strNewLine;
end;
{ Save string array to textfile (overwrite, no append!) }
SaveStringsToFile(strFilename, a_strTextfile, False);
Result := True;
end;
Результат тот же.
