Backing up multiple databases to the same point in time
I am assuming that your task is to create a set of backups where you can restore all of them to a single static (no open transactions) point (all in sync).  Similar to what a quiesce point will do for you in DB2.  Unfortunately there is nothing in SQL Server that does exactly that.  However, assuming your databases are in FULL recovery mode, you can do something similar.

You can create a single MARKED transaction across all of the databases at once.  Then you take a transaction log backup of each database.  Assuming you are keeping up with your log backups (which you should be anyway) log backups don't take very long.  And there is no need to stop anyone from being in the system (except maybe long enough for you to create your marked transaction).

At this point if you need to do a restore then you do a RESTORE STOPBEFOREMARK on each of your databases.  This will restore all of the databases to the same point (based on your transaction).  Note: There is also a STOPATMARK if you want to include that transaction.

If you want an example I've got one in the link above along with quite a bit of additional reading.

I realize this doesn't exactly answer your question but hopefully it solves your problem.