In order for us to understand your scenario and assist you in the best possible way, could you please provide us some more information:
1) How do you want to pass the variable to the PrepareMapping()
2) Do you want to use the variable only once to update the database schema?
3) Do you want to change the variable and the mapping at runtime?
I also suggest you to take a look at the Artificial Types
API provided by Telerik Data Access
which gives you the opportunity to your persistent model during the runtime.
I am looking forward to hearing from you.
OpenAccess ORM is now Telerik Data Access
. For more information on the new names, please, check out the Telerik Product Map