hi i am not understanding your question clearly 

1)you can pass datasheet value to test during run time 
DataTable.SetCurrentRow(1) 
var= Datatable.Value("Column Name","Sheet name")

2) you can write value to datasheet during run time 
DataTable.SetCurrentRow(2) 
Datatable.Value("Column Name","Sheet name") = Value 

Dear Raja First 1 is right ans.

Hi, Srinivas

I thought your miss guessed. Two ansewers are wrong ones 
and question is too clear

My answer is by using "Add parameter" method we can done 
this. please check out the example.

datatable.addsheet("lakshman").addparameter("column one 
name","value")

09860054593

we can add runtime parameter to data sheet as follows
syntax:
  Datatable.Gtglobalsheet.Addparameter("parameter name" , 
value)