You can still configure multiway to use just about whatever regex you want. We are only using TMSPE for Jabber/Movi - everything else is either manually configured or configured via TMS.
As an example, we use a "102" prefix, followed by a unit's unique E164 number, followed by our SIP domain e.g. 102(\d+)@ourdomain.com
Conductor seems to accept any Regex a VCS tranform or search rule would, it just has to be a valid SIP URI.
Yeah I wish that was the case, but you can only do that while using TMSPE. It's a bit of a gap in capability but unlikely to be fixed because of Cisco's drive to get everyone on CUCM.
The only way for manual/TMS provisioned endpoints to get a multiway URI configured is manually.