Here are the declarations that you need to use this DLL in Delphi 2 and 3:

Procedure IDX_SetIndexDirectory(S,SerNum:PChar); stdcall; external 'idxsrch.dll';
Procedure IDX_SetExcludedWords(S:PChar); stdcall;  external 'idxsrch.dll';
Procedure IDX_AddExcludedWords(S:PChar); stdcall;  external 'idxsrch.dll';
Function IDX_AddExWordsFromFile(FilePath:PChar):integer; stdcall; external 'idxsrch.dll';
Function IDX_SetExWordsFromFile(FilePath:PChar):integer; stdcall; external 'idxsrch.dll';
Procedure IDX_AddAlphaChars(S:PChar); stdcall; external 'idxsrch.dll';
Procedure IDX_SetAlphaChars(S:PChar); stdcall; external 'idxsrch.dll';
Procedure IDX_AddNonAlphaChars(S:PChar); stdcall; external 'idxsrch.dll';
Procedure IDX_SetNonAlphaChars(S:PChar); stdcall; external 'idxsrch.dll';
Function IDX_AddKeyWordsFromFile(nID:integer;WType,FilePath: PChar):integer; stdcall; external 'idxsrch.dll';
Function IDX_RemoveKeyWordsFromFile(nID:integer;WType,FilePath: PChar):integer; stdcall; external 'idxsrch.dll';
Function IDX_AddKeyWords(nID:integer;WType,Words: PChar):integer; stdcall; external 'idxsrch.dll';
Function IDX_RemoveKeyWords(nID:integer;WType,Words: PChar):integer; stdcall; external 'idxsrch.dll';
Function IDX_DoSearch(EX:PChar; Precise: integer ):integer;stdcall; external 'idxsrch.dll';

