The method of including your own custom traffic in your own regions is different depending on whether you are using 2004 or 2009 before installing the new SP4 patch, or after installing SP4 in 2009. After 2009 SP4 and in 2010 the 'trackside objects' method is applicable.
If you would like to tell me which version you will be using, I will point you in the right direction.
Scottish