Intel IPP 7.0 validated on following compilers along with intel C++ compiler,
- Microsoft Visual Studio* 2010
- Microsoft Visual Studio* 2008
- Microsoft Visual Studio* 2005
You can try with Visual C++ 6.0, this article might be useful. Just to clarify, this article refer not only to IPP 7.0 also describing how to compile earlier versions of IPP with older version of Microsoft * Visual Studio (like ver 2003).
There is nothing inherit in the library that prevents you from using VC 6.0. You will have to do more work to make the samples work, since they have been only validated and configured for later versions of VC. However, the libraries can be linked with applications that are built using VC 6.0 -- please see the links that my colleague, Naveen, provided for more information.