You may migrate an existing XSLT script to NiceXSL by using the XSL2NiceXSL.xsl script. This produces reasonably formatted NiceXSL, but you may well be able to sharpen up some of the source text. The script should run with any XSLT 1.0 or 2.0 processor. The author has used it with Xalan and Saxon 7.
Once you have NiceXSL sources, you maintain them and translate them to XSLT in order to execute them. You use an entry point in nicexsl.jar appropriate to your environment.
See Command Line Usage, ANT Usage or Eclipse Usage.You may find a very brief example of NiceXSL in the Overview
The XSL2NiceXSL.xsl stylesheet that reverse engineers XSLT stylesheet into NiceXSL provides a much more substantial example. This code supports pretty printing with a variety of new-line, quote and special characters and so may provide some inspiration for those struggling with accurate text formatting. This stylesheet is generated from XSL2NiceXSL.nxsl.