samsung note 3, rooted, running stock ROM
macbook pro running OSX 10.8.5 mountain lion
directions are for OSX, sorry - i'll try this out on windows and linux later and update.
i'm not quite sure which of these are required, so i'll list them all:
1) setup a new APN on your phone with the following:
[go to settings >> connections >> more networks >> mobile networks >> access point names]
APN type: dun,default,mms,fota,supl,hipri,admin
APN protocol: IPv4
APN roaming protocol: IPv4
now select the new APN, reboot your phone if it doesn't connect.
**i DID edit the /system/csc/customer.xml file to change a few of the APN settings, like changing the APN protocol from ipv6 to ipv4, making profiles editable, etc. - you need root to do this - but changing that file shouldn't be required
2) i haven't tested this out on windows or linux yet. you might have to install the USB drivers to create a new connection.
connect your phone via USB. in OSX, go to network preferences, click on the (+) to add a new interface, then select SAMSUNG_Android from the list of interfaces. i would assume in windows and linux you'd just create a new dialup connection, then use whatever the phone shows up as the name for the modem/interface - but i'll go back to this later.
make sure the telephone number is *99#
user and password you can leave blank
click on "advanced.." and configure advanced settings:
model/connection type: GPRS (GSM/3G)
DNS: set to whatever DNS servers you want, or leave blank to go with t-mobile's (though i don't recommend that) - i use dnscrypt so mine is 127.0.0.54 but that won't work for you - here's a couple free/uncensored/unlogged DNS servers from censurfridns: 188.8.131.52, 184.108.40.206
PPP echo packets OFF (unchecked)
TCP header compression ON (checked)
now click "apply" to save the settings, then "connect"!
i always use a VPN - if you get any t-mobile tethering upsell pages, you can use a VPN to encrypt all your traffic, or set your browser's user agent to Safari on OSX to get around it. so far i haven't run into any issues like that, and it's pretty fast.. i get anywhere between 15 - 30 Mbps. here's a screenshot from speedtest.net connecting directly: