できました
きっちゃないコードですけど↓

procedure TForm2.PgAtoClick(Sender: TObject);
var
NanGyouMe:integer;
begin
MyList.Col:=0;
NanGyouMe:=MyList.Row+MyList.VisibleRowCount-1;
MyList.TopRow:=NanGyouMe;
MyList.Row:=NanGyouMe;
end;

procedure TForm2.PgMaeClick(Sender: TObject);
var
NanGyouMe:integer;
begin
MyList.Col:=0;
NanGyouMe:=MyList.Row-MyList.VisibleRowCount+1;
if NanGyouMe<1 then
begin
MyList.TopRow:=1;
MyList.Row:=1;
exit
end;
MyList.TopRow:=NanGyouMe;
MyList.Row:=NanGyouMe;
end;