This was a quite high rated AHA idea. So the SafeLinx team and Domino team teamed up to implement it.
The flow is integrated into the SafeLinx UI and SafeLinx also allows ACME challenge "passthru".
There isn't any change in CertMgr needed. It is implemented in a way that you could implement your own integration flows.
If you have a specific integration idea, ping me. I can point you to the right direction.
This is a companion discussion topic for the original entry at https://blog.nashcom.de/nashcomblog.nsf/dx/hcl-safelinx-1.4.2-available-new-best-friend-domino-certmgr.htm