So tried new arrangement myself today for first time - normally I wouldn't get the HEX between T2/3 and T5 but I went that way today. There are now dedicated ticket machines to get the free transfer ticket - you can't get the free tickets from the normal machines.

At T2/3 there only seemed to be one machine I could spot and that was situated just to the left of the barrier line.





Basically just select the number of tickets you want and press print.





Then just use the ticket in the ticket barrier and down the lifts to the platform. When you exit at the other station (for me it was T5) the ticket is captured by the barrier so you can't keep it as a souvenir

At T5 there were two free ticket machines I spotted down at platform level:



At ground floor level I couldn't see any free ticket machines, just the normal ticket machines, so at T5 it seems you can only get the free ticket at platform level.

I haven't seen the set up at T4 yet, may try and head that way in the near future to have a look.

EDIT: just to add I assume like the tube you can use an oyster or contactless card instead to tap in and out, so getting the paper tickets isn’t compulsory.