seeking help on NONMEM code for simulation of Repeated Time to Event Data

Dear NONMEM Users, I have some questions about how to accomplish the following tasks in NONMEM, would you kindly share your experience with me or provide some suggestions? I'm trying to make a simulation that involves dynamic dosing. Here is the algorithm of simulation: at time 0, a dose is given, then the time to the first event will be simulated based on a certain survival function which depends on the drug exposure. Next, conditioning on that simulated first event time, a second dose will be introduced, and again time to the second event will be simulated. This will be repeated until a certain cut off time point. My specific questions are: 1. since the dosing history will be depending on the simulated event time, I cannot construct the dosing history in NONMEM data set a prior, how can this be done? 2. The survival function is a function of the time-varying drug exposure, therefore I need to inverse an integral which does not have a closed form (i.e. only expressed in differential equation), how can I do that? Your help will be much appreciated! Yaming Hang