There is no documentation available around it as it is custom implementation work and Consulting are the best people to say about it. Only they can explain if this is feasible to have Send Time Optimization on v6 or not. My knowledge says that custom delivery connector should be able to accomplish this.
Can you expand a little about a "custom delivery connector" for v6 of Adobe Campaign (classic).
Is this the type of thing that would enable Send Time Optimisation (delivering a delivery to customer at best day/time based on previous engagement) or are you talking more about a solution to handle local timezones.
If there is any documentation you could share, that would also be helpful.