Setting Up a Pyramid Swim With Fixed Time Intervals/Rest

I am having some trouble setting up a pyramid swim with fixed time intervals for the rest.

I want to do this:  Swim 100, 200, 300, 400, 500, 5, 4, 3, 2, 1.

The rest I get between steps will be [(2:00 x distance) - time it took to swim].  So, for example, on the 500, I will have 10 minutes to complete it.  Whatever I finish under 10 minutes will be my rest before I start off for the next step. 

The only way I have found to set up a time interval for rest is when I do repeats, but in this case I am not repeating anything, just moving on to a new step.

Thanks in advance for any help you can provide.