How to use DATEADD function to convert epoch to human readable CST with day light savings into concern?

Hi

  I am using the DATEADD function to convert my epoch date format to human readable format.So right now I use

DATEADD(s,[epoch date],'1970-01-01')

To convert that to CST I am not sure if I need to use

DATEADD(s,[epoch date] - 21600 ,'1970-01-01').  Please confirm this for me.

Also now I need to take into consideration, how to manipulate the function so that I could take the day light savings also into concern,Could anyone help me on this one please.

Cheers!