I'll add one data point: I traveled a few days ago ORD-DOH-KUL (QR) and KUL-PNH (MH) with the MH leg on a separate ticket, all in J. I asked a couple different ways at ORD, emphasizing the "OW partners" part, whether they could print boarding passes for the KUL-PNH leg. I got a polite but very direct "no." Didn't push it because we weren't checking bags, and we ended up collecting the MH boarding passes at a KUL transit desk airside.