In the past I have used 2 techniques to by pass triggers. One is to create a dummy temp table on the connection and then check in the trigger for the temp table's existance. This method provideds a simple connection based bypass with automatic cleanup since the table is removed when the connection is closed.
create table #dummy (dummy int)
in Trigger:
if Object_id('tempdb..#dummy') is not null
return
The second method is to create a dummy global cursor and then check for the existance in the trigger.
Declare TriggerSkipCursor Cursor Global For
Select '1'
Open TriggerSkipCursor
in Trigger:
if CURSOR_STATUS('global', 'TriggerSkipCursor ') = 1
return
Both these methods have worked well for us.