HTC Mozart owners residing in India are receiving an update to be able to use Internet Sharing, according to a report at welovewp.hk. Aviraj Ajhekar, an employee at Microsoft India, has published an article stating his Mozart received a firmware update and was then able to tether.
Unfortunately, welovewp.hk reports that a similar update received in Hong Kong doesn't enable the feature, which further confirms the final decision being up to carriers. We've recently covered ThreeUK allowing Internet sharing on the Samsung Omnia 7, as well as LG Germany.
Have you received a firmware update that enables this WiFi feature?