Creating Custom Field Types with Additional Column Settings

Question

I am trying to create a Custom Field Type which is same as Multiple lines of text field with the following additional:

• It has one extra text box in the Additional Column Settings section when creating the question

alt text http://img685.imageshack.us/img685/3338/multilineoftextwithrefe.png

• When rendering the question, the value in the text box to be displayed before the text box as a link

alt text http://img218.imageshack.us/img218/1263/questionwithreference.png

Does anyone know how I can achieve this?

Thanks in advance!