How can one delay a sequence? (MATLAB 2010)

This shouldn't be so hard, but I can't figure it. On Simulink, I'm using and S-Function to create a recursive least squares parameter estimator. So far, I'm using a delay blocks, but if I want to estimate a more complex model, it's not going to work. I have seen examples, in which people can crop the vectors, but I can't remember. What I want is:

Lets say I have the sequence: y = [ 1 2 3 4 5 6]

I want to have y(k-1) = [0 1 2 3 4 5 ] y(k-2) = [0 0 1 2 3 4 ]

and so on (There are 0s because it is supposed that before t=0, the value of the signal was 0). So, how do I go on about it?