I've not tried. Honestly, it was as simple as installing SynCE and connecting the device... it automatically connected after that.
http://www.synce.org/moin/SynceWithUbuntu
Follow it to the point where it tell you to run "synce-pls" and after you run that, stop there.
I have a feeling if you follow the rest, you'll break tethering. Then once you connect the device, you'll see a plug with an exclamation point... but if you look at the phone, it looks like it thinks its connected to ActiveSync. Then disconnect it, start internet sharing on USB, then plug it back in... you'll see it get a connection to the device then the plug with the exclamation point will come back... but you'll be able to browse completely fine.
BTW... 19 minutes for 151.05MB = 7.95MB/min = 132.5KB/sec = 1056kbps!!!... and I was browsing at the same time.
EDIT: For the non-believers (because I know there will be), here's a testmy.net that not only confirms I'm using linux but confirms that I'm getting sustained download speeds (its a 12MB test file for download, 3MB for upload)
:::.. Download Stats ..:::
Download Connection is:: 1066 Kbps about 1.1 Mbps (tested with 12280 kB)
Download Speed is:: 130 kB/s
Tested From::
http://testmy.net/ (Main)
Test Time:: 2008/05/14 - 1:29am
Bottom Line:: 19X faster than 56K 1MB Download in 7.88 sec
Tested from a 12280 kB file and took 94.362 seconds to complete
Download Diagnosis:: May need help : running at only 24.39 % of your hosts average (spcsdns.net)
D-Validation Link::
http://testmy.net/stats/id-ZHT6WX245
User Agent:: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9b5) Gecko/2008050509 Firefox/3.0b5 [!]
:::.. Upload Stats ..:::
Upload Connection is:: 737 Kbps about 0.7 Mbps (tested with 2992 kB)
Upload Speed is:: 90 kB/s
Tested From::
http://testmy.net/ (Main)
Test Time:: 2008/05/14 - 1:31am
Bottom Line:: 13X faster than 56K 1MB Upload in 11.38 sec
Tested from a 2992 kB file and took 33.267 seconds to complete
Upload Diagnosis:: Awesome! 20% + : 169.96 % faster than the average for host (spcsdns.net)
U-Validation Link::
http://testmy.net/stats/id-CJLXSOBET
User Agent:: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9b5) Gecko/2008050509 Firefox/3.0b5 [!]