outliers for seasonal adjustment

[punjaphp]

Hello,

I want to filter out the outlier (e.g. flood period) of my dataset when doing seasonal adjustment.
What are the program commands to manually set outliers of the data series for both X12-ARIMA and TRAMO/SEATS methods?
say, I want to set the period of 2011.4 as an outlier of quarterly GDP series

Thank you very much