Campaign Determination in Sales Order Line Item

Dear All,

I have a requirement where in I want to capture the campaign in the sales Order. The scenario goes like this.

1) I want to execute a campaign for a promotion to specific customers in the form of coupon code or discounts.

2) When I create a Sales Order for that customer, I want to see the discount coming up when the campaign is selected in the Sales Order Line Item. Once the camoaign is selected it should automatically trigger the disocunt conditions.

Any clue on how to handle this would be really helpful.

Thanks in advance

Kumar