Vertical typesetting in ConTeXt MkIV?

Section 6 of followingup sketches a preliminary support for CJK vertical typesetting in ConTeXt for LuaMetaTeX (aka LMTX). Unlike LuaTeX, which supports four directions, only two of which are properly implemented, LMTX only supports two directions, 0 (left to right) and 1 (right to left). In order to get vertical typesetting, LMTX recurs to a new and more customizable mechanism of orientations applicable to boxes with the following syntax:

%hboxes
hbox direction <0 or 1> orientation <orientation number> {content}
hbox orientation <orientation number> direction <0 or 1> {content}
%vboxes
vbox direction <0 or 1> orientation <orientation number> {content}
vbox orientation <orientation number> direction <0 or 1> {content}

In turn, there are four orientations with two anchors which are specified via numbers

orientation "<horizontal anchor (X)><vertical anchor (Y)><orientation (O)>
%X goes from 0 to 6
%Y goes from 0 to 3
%O goes from 0 to 3

After a really graphical explanation of orientations, Hans Hagen gives two working examples in pp. 48-49.

I guess they are a decent starting point.