How do you define a new language specification for color syntax highlighting in Xcode 4?

It appears that this just isn't possible yet. According to this answer the API's that supported this in Xcode 3.0 were outdated even for that version, and have been completely removed in 4+.

There is a project called solarize that may do what you're looking for, but I didn't see any of the languages you listed and support for Xcode 4 is still limited. I personally use Xcode only for Objective-C programming, and then use eclipse or TextWrangler for the rest

Eclipse for Mac OS X

Eclipse is great for the more intensive projects, that have multiple classes, and are actual projects. It's mainly developed for Java, but also supports Python, C/C++, PHP, and Lisp (probably even more)

TextWrangler

TextWrangler is great for small edits or files. Things that I need to pull up quick, and make smaller edits to and supports tons of languages as well.

It appears that Xcode can even open external editors when the files are associated to that editor. While this isn't the perfect solution, it appears to be the only one for now.