There is no transit route from T1 to T2. You'd have to clear immigration in T1. Then you go landside and take the people mover to T2. Then you can either go to a non-Schengen or a Schengen lounge in T2.

If you opt for a Schengen lounge, there will be a central security control to pass after which you can access the lounge. You can leave T2, taking the people mover to T1. There you'll have to pass another security control.

If, instead, you wish to visit a non-Schengen lounge in T2, you'd go through passport control. No security control as, in the non-Schengen area of T2, these are just before the gates. So you can go to the lounge. To get back landside, there will be immigration once again. Back in T1, security control.