This is imposible by the very nature of triggers. Triggers are supposed to be independant. However, if it is badly required you could create yourself a table to hold any values you need to pass into your trigger. The trigger can then interigate the table.
If you need to make sure the line in the table is unique to that connection, put in the SPID. This is available to both the stored procedure and the trigger.
Be careful. This may not work if you use the procedure so often that two lines could be added to the variable table.