Hamish:
since v.mkhexgrid is just a python script, you can just
download it by hand and put it somewhere in your path.
Giovanni:
that's what I did, even before trying with a self-compiled
6.4.3RC2, but I cannot find the extension under the GUI menus
I think support for adding addons to the wx menus is still to-do.
(there was some support for that in the tcl/tk gui, .. maybe
two ways IIRC, one via GEM the other via.. ?)
otherwise you need to run it from the command line, or edit
the menu file yourself to add it.
see $GISBASE/etc/wxpython/xml/menudata.xml
Is trunk the latest 6.4.3? I thought it wad GRASS 7.
trunk is grass 7.
releasebranch_6_4 is what will become 6.4.3.
Hamish