I found this also to be useful...........
http://community.vsl.co.at/forums/p/17411/124464.aspx#124464
"In Logic's environment, create a new multi-instrument - - this will have 16 channels. Wire the multi-instrument to Instrument 1 on the MIxer page of the Environment. (To move an object from one layer of the Environment to another, select the object, hold down the option key while selecting the layer of the Environment to which you wish to move the object.) Name the Multi-Instrument something like VE 1. After you have done this, load a multi-channel instance of VE into Instrument 1. Go to the arrange page. You will find that, when you right-click or contol-click a track, you can reassign it to VE 1, channels 1 - 16). Load the instruments into VE as you desire.
IMPORTANT NOTE: If you are using what is, at present, the most current OSX version of VE - - dated 2007-11-08 - - DO NOT ATTEMPT INSTANTIATION OF MORE THAN ONE INSTANCE OF VE. ((This will still give you 16 channels to work with.) If you instantiate more than one instance of VE, it will work as long as the file is open, but once you've saved and closed the file, attempting to open it again will result in a crash. In other words you will not be able to re-open the file!
It is important to remember that, in Logic, MIDI Volume (CC7) changes will affect all 16 channels of a multi-instrument simultaneously. Since this is rarely desirable, use MIDI Expression (CC11) to affect changes in level for each channel - MIDI Expression settings can function independently on all 16 channels."