As part of His Holiness Sakya Trizin's tour to Malaysia, His Holiness, the present head of the Sakya lineage, will be conducting a two-day Kalachakra Empowerment at OCM Indoor Sports Centre opposite Stadium Negara, Kuala Lumpur from 2 p.m. onwards on the 29th and 30th September, 2007.
From my source of information, these session will be until night. Admission is free.
Kalachakra is considered the most advanced form of Vajrayana practice and it certainly is one of the most complex systems within tantric Buddhism. For more information about what Kalachakra is, you can visit wikipedia or here.