dbx_page_sidebar successor in 2.6?

I’m updating my plugin, Bunny’s Language Linker. I used the dbx_page_sidebar hook to insert a meta field into the Edit Page admin screen.

In 2.6, this doesn’t work anymore. Which hook do I need to use to add an “option” (you know, those blue expandable “boxes” at the bottom of the Edit screens) in 2.6?

Thanks for the help.