nsisXML is a plugin for NSIS to read XML nodes via XPath:

a) Get MSXML 4 parser:
http://www.microsoft.com/downloads/details.aspx?FamilyID=3144b72b-b4f2-46da-b4b6-c5d7485f2b42&DisplayLang=en

b) Learn XPath
http://www.w3schools.com/xpath/default.asp

c) Try the functions:
1.- IsXML4.- Function that detects to version 4 of the msxml.
2.- tidy.- Function to make a tree style nodes in the xml.
3.- xPath.- Function to parse the xml with XPATH instructions

See examples.

Joel Almeida Garca.
aullidolunar@yahoo.com.mx