The stock ROM alone won't have wifi tethering enabled, since Sprint wants to charge you for it. However, if you get ANY of the reputable 2.2 custom kernels (or a ROM that contains said custom kernel), you will be able to wifi tether. If you want to preserve the stock look and feel but have the bonus features, check out this kernel:
[Kernel]netarchy-toastmod, updated for 2.2 - Version 3.7.6c - xda-developers
Flashing this kernel also gets you USB and wifi tethering as well as the boost in framerates and disabled perflock (enables CPU throttling).
Reminder: do a nandroid backup before flashing anything. Make it a habit