Cm10 built in tethering works just fine, its in settings>more>tethering and Portable hotspot, you can use WiFi,Bluetooth,or USB. I only tested WiFi but I'd assume the other 2 do too. Same restrictions as on stock though, you have to use the proxy or some other method to get around metros block, otherwise it just doesn't load anything. I connected with my tablet and ran a speed test, got about the same speeds as I get on the phone itself, 8mbps down, 3mbps up.
(And since people probably won't believe metros network can actually do that,
http://www.imgur.com/2RNJEf2.png http://www.imgur.com/ng3EZPY.png I had 2 bars at the time of tests.)