Set Value
This sets the client variable with name "variableName" to the "value":
context.ClientVariables.SetValue(variableName, value)
	 
context.ClientVariables.SetValue(variableName, value, "Maximum
		  Age in Seconds")
	 
Be aware that cookies are generally deleted by the browser when the browser is closed. If you want the cookie to last longer, give it a maximum age. For example, to set a cookie that is good for one week, you would use:
context.ClientVariables.SetValue("CustomerPortalCartNumber", "my
		  cart number", 604800)