I just got a Treo 650 with Alltel. I was little frustrated that FC6 wouldn't see the Treo when I would hit hotsync. I did some googling and found a reference and gave it a try.
and add the following lines
<!-- Treo 650 -->
<device vendor_id="0830" product_id="0061"/>
I don't *think* it matters where you add the lines, but I added it in the Palm section just to be sure.
Then just go through the usual setup in Evolution or the GPilot Applet. All of the conduits are working great for me.
Good luck! Tony