Fire And Motion.

type
  TSHSetFolderPath = function(csidl: Integer; hToken: THandle; dwFlags: DWORD; Path: PChar): HRESULT; stdcall;

function SetFolderDir(csidl:Integer; newDir: string): Boolean;
var
  hd: Cardinal;
  SHSetFolderPath: TSHSetFolderPath;
begin
  hd := LoadLibrary('shell32.dll');
  Assert(hd <> 0, 'shell32.dll not found ?');
  SHSetFolderPath := GetprocAddress(hd, PChar(231));  //ansi version,unicode version is 232
  Result:= Succeeded(SHSetFolderPath(csidl, 0 , 0, PChar(newdir)));
  FreeLibrary(hd);