So I saw in a Blackstar forum where a guy hooked up an HT60 successfully, so I decided to just give it a go. TRS cable from the amp to the HX effects will switch the channel if you set the switch to monitor Tip or Tip/Ring. Ring only will change the Voice on the clean channel.
There is a slight audible thump when changing channels that is not present using the OEM footswitch, but other than that is appears to be functioning. No sparks, smoke, fire, ect. so far.