Paul King explains how to use the DirectoryEntry object to manipulate MSMQ properties.
Our support website does a pretty good job for telling you how you can modify the MachineQuota setting for MSMQ. Unfortunately, if you need a way to do this programmatically and your installation happens to be in "Domain Mode", then there really isn't enough information here. Fortunately using the DirectoryEntry object makes this a pretty easy task.
Short and too the point. Too many people using MSMQ approach it with a workgroup mind-set and don’t always appreciate how much more there is to the product with Active Directory Integration.