...but the build script is not even mine, I just want to run it.
I cannot change the Ant script to include an explicit <classpath>; for example, I have it checked out from a public Subversion server. What can I do?
If necessary, you can use Additional Classpath in Ant settings in the Options dialog. Ant-based compilation will then pick up any JARs you added. This is not recommended when writing your own scripts as it can make them dependent on libraries NetBeans itself uses, and makes your scripts inherently less portable. See if you can get the author/maintainer of the script to fix it to be more portable.
Applies to: NetBeans 4.0 and later