http://www.modaco.com/content/Windows-Mobile-News/265615/How-to-install-and-USE-net-Compact-Framework-3-5-WITHOUT-upgrading-your-ROM/#entry882822

NetCFCfg.CAB ( 31.17K )

NETCFv35.wm.armv4i.cab ( 2.58MB )

- Downloading and installing both CABs below (to internal memory!)
- Running '.Net Configuration' from your Start Menu
- Navigating to the 'Device Policy' tab and selecting version 3.5
- Selecting 'Apply' then 'OK'

You'll be aware that it offers a number of enhancements in features, stability and performance, and you'll likely also know that it provides full backwards compatability with previous versions of the Compact Framework. What you may NOT know is that when CF 3.5 is installed on a device, applications that target previous versions of the Compact Framework will continue to run against the old versions, and 3.5 and previous versions will live side by side on the device. Only when new devices come along will we see ONLY 3.5 on a device.

This presents a number of problems, namely

• Users who deploy CF 3.5 to their device but use applications targeting older versions will not benefit from the 3.5 performance improvements
• Developers who develop apps for pre CF 3.5 frameworks cannot easily test their applications ready for when 3.5 only devices come along

Thankfully, help is at hand in the form of a little known Compact Framework 3.5 powertoy named '.Net Configuration'. The application, which is available in this download at Microsoft, provides the user with full granularity of control over the .net CF on their device. You can see installed versions, change the used CF version for a particular application or change the used CF version for all applications run on your device! Perfect!