Paper addresses the process of dynamic data flow analysis using virtual code integration (VCI), often refered to as dynamic binary rewriting. This article will try to demonstrate all of the techniques that were applied in the SpiderPig project. It will also discuss the main differences between the methods that were employed and those used in other available software, as well as introducing other related work. SpiderPig's approach was found to be very fast and was transparent enough for reliable and usable data flow analysis. It was created with the purpose of providing a tool which would aid vulnerability and security researchers with tracing and analyzing any necessary data and its further propagation through a program. At the current state it works on IA-32 platforms with Microsoft Windows systems and it supports FPU, SSE, MMX and all of the IA-32 general instructions. SpiderPig also demonstrates the usage of a virtual code integration (VCI) framework which allows for modifying the target application code at the instruction level. By this I mean that the VCI framework allows for custom code insertion, original code modification and full customization of the original application's code. Instructions can be swapped out, deleted or modified at a whim, without corrupting the surrounding code and side-effects of the modification are resolved.