Technically there is no need for a software update for the box as access to on line services is through the Portal. In other countries' versions of the portal (notably Germany where I believe the software "apps" originate) have other services including catchup from some of their channels. The range can be seen that the site they use to demonstrate the facility at trade fairs. Humax TV Portal (press return to progress through the disclaimer).
Wait for Humax to make them available on their portal as that is where the software and access points are. There is no "app store" facility for consumers.
I also suspect that their developers are busy working on the YouView boxes due out next year as presumably they do not want the official developers stealing their glory and getting to market too far ahead of them.