Simple effects for 3-way interaction


I'm doing a regression analysis with a continuous outcome variable (motivation), 2 continuous predictor variables (income and age), and 1 dichotomous predictor variable (condition). I have determined that there is a significant 3-way interaction, and that in both conditions, there are significant 2-way interactions (income x age predicting motivation).

What I want is to get the simple effects (a la Aiken & West) of these 2-way interactions. How can I do this?