How to attach Tor Browser to HTTP proxy before Tor?

I’m running a HTTP proxy at in a workstation. So, how I connect Tor Browser to before it accesses the Tor network? In non-whonix workstation (think debian > whonix-gw) it works well. But in Whonix I can’t do it cause of unusual usage of socket file in the browser proxy settings instead of bare gateway proxy IP address and port (see the “anon-ws-disable-stacked-tor considered useless” topic).

Related documentation:

But this might be most on topic:

Tor Browser Advanced Topics

Great thanks. God bless you, Patrick!