You must use a simulator which explicitly supports PHost. BSim used to be a popular choice. Internally, it supports only PHost 2.x, therefore results will be slightly off in some cases. CCBSim supports all PHost 3.x subtleties as well as PHost 4.0, but it has some problems with very long fights. Recent EchoView versions have a PHost 3.x/4.x simulator built in, too. As of December 2006, PlayVCR has a built-in multi-ship simulator ("CCBSim 2.0") which supports all features of PHost.
If you are using 100% "standard" combat, you can try to use a HOST simulator, such as the one built into VPA and Winplan. Results should give you a vague idea on the outcome, but don't bet on it.
