Firstly I'll say I'm using this on wine-1.1.9, any other wine versions might have unexpected (or expected) issues.
it's a bit verbose to explain everything in minute details so instead I have written a script to (hopefully) do it for you, it should be attached to this post.
Before running the script rename your Tribes2/GameData/base/T2csri.vl2 to T2csri.vl2.bak, the script will leave this untouched but assumes it to be a 'clean' copy from which it builds the new.
Extract the script,
$ chmod +x t2hack.py
$ ./t2hack.py /path/to/your/Dynamix/Tribes2/
you should now be able to launch T2 under wine (using Wine Tribes2.exe -online) but as the name suggests it really is just a nasty hack
But for me at least it's still more convenient than using Windows.
You will lose the server browser (use instead the MaxOGC link in the sticky in the main forums) meaning you'll have to join servers by IP but I'm afraid I'm unfamiliar with what console command allows that... One of the PJ scripts adds a 'join IP' button to the server list screen, but I'm not sure exactly which. Favourites still retains a list of servers but it can't query them.
Surprisingly, you also seem to be able to actually register accounts using this (which I tested once and managed to get through without Wine locking up), but if you do so, afterwards you'll have to quit and re-run the script in order to hard code the certificate for it.
You'll also have to re-run the script if your IP changes.
Hopefully it'll work but any problems let me know (BTW: if your env python variable is set to a Py3k interpretor you'll have to run it under a Py2.x interpretor instead; I think most if not all distros are still 2.x though)
A brief explanation of the files within T2csri.vl2 it modifies are:
scripts/autoexec/t2csri_list.cs -> renamed to t2csri_list.cs.null to prevent it being executed. This disables the server browser, and something else which caused wine to lock up randomly ish.
t2csri/ipv4.cs -> changes ipv4_getInetAddress() to define the computer's IP address at the top of the function (workaround for intro screen wine lockup)
t2csri/clientSide.cs -> changes t2csri_getAccountCertificate() to include the details from the public.store file (workaround for the truncated certificate issue)