If it's locked to Rogers currently, you'll have to get them to unlock it. Once done all you'll need is a Telus SIM card and a plan.
For information on unlocking with Rogers, please see their page here. I believe the unlock fee gets waived December 1st (all carriers).
The bring your own device plans are listed here:
Just make sure in the top right hand corner you have the correct province selected as that will impact the plan pricing.
You can also bring your current Roger's phone number over to Telus by getting your Roger's account or security pin. Do not cancel the Roger's account. When you create the Telus account, you give them your Roger's phone number and either the account number or security pin and they can bring that phone number over. You will have mixed service between Roger's and Telus for up to 2 hours. Meaning you may be missing calls or unable to dial out in that period. Once you receive a text saying that your Port is completed. Then you will have service 100% on Telus and all your services will be working.