To enable Friendly URLs in MODx, you would just need to do the following:
1. Log into MODx
2. Click the Tools Menu Configuration
3. Click the Friendly URLs tab
4. Change the radio option Use friendly URLs to Yes
5. Click Save
You now need to upload an .htaccess file to your website wwwroot folder this will tell the web server the processing rules for Friendly URLs.
Below are the contents of the .htaccess file which you should create and upload.
These processing rules will allow .xml & .html files to be rewritten as Friendly URLs with MODx and it will exclude any .html, .xml files located in either the manager or assets folder.
# Helicon ISAPI_Rewrite configuration file
# Version 3.1.0.48
RewriteEngine On
RewriteCompatibility2 On
RepeatLimit 32
RewriteBase
# Block external access to the Helper ISAPI Extension
RewriteRule ^.*\.isrwhlp$ / [NC,F,O]
RewriteRule ^/(?!(?:manager|assets)/)(.*)\.html(?:\?(.*))?$ /index.php?q=$1?2&$2: [NC,L,U]
RewriteRule ^/(?!(?:manager|assets)/)(.*)\.xml(?:\?(.*))?$ /index.php?q=$1?2&$2: [NC,L,U]
