Items required:
Unlocked (with ChevronWP7 or Developer unlocked) WP7 device
ChevronWP7 Ringtone Installer
MS Expression Encoder or other audio conversion software
XAP Installer (Tom XAP or WP7 SDK Application Deployment)
TouchXplorer: http://forum.touchxperience.com/down...31bdc3bee51b36

1. Choose files to use as alert/alarm sounds. If in WMA format already skip to step 3.
2. Using MS Expression or equivalent, convert files to WMA.
3. Rename desired alert tones to Alert-01.WMA (you can subsitute the number based on what sound you'd like to replace, because we will be overwriting the corresponding sound) or for alarms it'd be Alarm-01.WMA (or corresponding). NOTE: You will be overwriting the sounds so make sure you review all sounds and make sure you don't mind not having them anymore if you're overwriting them.
4. Using ChevronWP7 Ringtone Installer deploy these files to your device through an XAP Installer.
5. Install TouchXplorer by deploying XAP to device.
6. Using TouchXplorer navigate to My Documents>My Ringtones and highlight desired alert/alarm sound. Bring up the menu and copy it. Navigate back to root menu and go into Windows. Paste alert/alarm sound; it will ask if you wish to overwrite, click yes. Done. Repeat for all other alert or alarm sounds.

NOTE : I believe this will only work on HTC phones ATM, since TouchXplorer only works on HTC devices for now.