I guess the first question for the OP is to see if the ticket in your hand is already RFID-capable. Look on the back for the MDE logo, a Mickey head inside a circle. If it's there, then there's no additional conversion necessary and you shouldn't have any problem linking the ticket to your MDE profile.
If it's *not* there, you may still be able to link it to your MDE profile. On the phone app click on Enter ID, and then "Where can I find my ID number?", then "Have a ticket purchased before Oct 2011". It'll give you various configurations of what your ticket might look like. Find your ticket and enter it.
I *presume* that this will get you access to making FP+ reservations. But even then you'll still need to get an RFID card. You may have to wait until you get there and visit Guest Relations to do that. Bring the ticket and they'll swap it for an RFID-enabled ticket. Hopefully the CM can link the ticket directly to your MDE profile, but you may have to go back in and enter it yourself.
Worst case scenario, you'll have to wait until you get there to trade in the ticket, get an RFID-enabled card and then make all of your FP+ choices at that time.
-Rob