Custom number used in formula for roll-up cost

[Lenford]

My client is interested in creating a custom cost value
that changes at some incremental rate as the project date
moves through sequential years; similar to the way the CRT
works in the Resource Information Dialog.

1.) how do I get the project date for an active cell
anywhere in the project timeline inorder to calculate the
proper percentage.

OR:

2.)is it possible to extend the functionallity of the
Resource Information Dialog; in particular the CRT to
include new column headers?

Can anyone help me with a solution?