If you have a dev/Chevron unlocked phone then this is about as easy as it will get to enable internet sharing/tethering and get interop unlocked (so you can play with the good sideloadable apps). It’s this simple:
1.) First install the WP Dev Tools and unlock your Samsung phone.
2.) Use the Application Deployment tool to send THIS to your phone. You do not need to run it and you can delete it after it has been deployed.
3.) Install the Diagnosis app by typing ##634#
4.) After the Diagnosis app starts type *#9908# and select ‘System Tweaks’ press ‘Save’ then ‘Close’ and RESTART your phone.
5.) Your phone now has internet sharing and as a bonus is interop unlocked!
PS: You need to have a recent firmware on your phone or your diagnosis app and drivers will not be new enough to work.
EDIT: I built the file deployer app using the tools provided by Heathcliff74 so many thanks to him! Also ADC is built in as well so no need to worry about that and I also upped the max number of connections from 3 to 5 devices.
NOTE: If you have internet sharing turned on (active hotspot) you will not be able to deploy XAP’s until it is turned off. Also, as with any xap, you need to have your screen unlocked to deploy.
These instruction, from voluptuary of XDA are about as easy as it will ever get. Aahh it reminds me of the good old days on XDA. Anyway, it does work and you need to have all of the Mango bits for it to work (including that last Samsung driver after mango was installed).