Get your vote in. Fair warning is that I would have to manually schedule this because I don't think OOTP can handle all-star games or series between leagues in an association.
That's going to mean issues on when to have it because I hate to manually edit schedules any more than absolutely necessary. I also want to note that even if we vote to have one we might not because I think that right now I would have to manually create all-star teams or even an all-star tournament and manually populate the teams with the players voted onto the all-star teams. I'd be willing to do it if most of the league wants to have one, but it would definitely be some work.
With all that in mind, my idea for when to have the game or series would be actually after the WBA Championship Series but before free agents declare, arbitration is decided, etc. Basically that 2-3 week dead period between the end of the season and the start of the real offseason activities.
Oh yeah, just like our other exhibition (the WBA Cup) injuries would be turned off so everyone would have no reason to wish their players weren't all-stars.