Using sales agreement component in opportunity component

Hi Firends,

  I have created one AET field in Sales agreement detail tab( Component name : BT107H_SLSA/ BT107H_SLSA/Details)  it has two drop down values 1) changed 2) unchanged.. if this field value is changed i need to display my custom configuration in opportunity details tab.... for achieving this as per my knowledge.. i need to write the code on DO_CONFIG_DETERMINATION( ) .... in the  controller class...  of Opportunity component details view but i dont know how to read the  field value from the sales agreement component...

Can any one help me out i can solve my problem.......

Regards

Sandya...