Looks like the HTTP commands for the playback transport control buttons that appear in the Vera web UI are located in the Vera plugin file called “I_KODIRemote.xml”
These would need changing from GET to POST HTTP commands.
However I think a username and password now also needs to be specified to access the Kodi JSON API, so not sure how you would handle that in this Vera plugin code ?
I wrote about sending HTTP commands from Vera scenes / LUA code etc here.