Microsoft CRM customization techniques are very diversified and based on the whole spectrum of recent Microsoft technologies. The main terms you should know are: Microsoft CRM SDK 1.2 and Visual Studio.Net 2003. And of course you should be familiar with all the legacy internet technologies, such as HTML, XML, XSLT, JavaScript and be good C#/VB/Net developer.

If you are developer who is asked: how do we customize Microsoft CRM