This SQL statement will do it for you. If you want it to be part of an IS project then make it the SQL of a SQL Script task.
declare @object_id int
declare @str varchar(255)
select @object_id = min(object_id)
from sys.tables
where name <> 'sysdtslog90'
while @object_id is not null
begin
select @str = 'truncate table ' + name
from sys.tables
where object_id = @object_id
print @str
exec (@str)
select @object_id = min(object_id)
from sys.tables
where object_id > @object_id
and name <> 'sysdtslog90'
end
If you are not happy with using the sys.tables view, then you could always define the table list yourself.