I sold my unincorporated client list and trailing commissions as goodwill. I believe this has a capital-gains-like treatment. How do I report this in Turbo Tax?

There was a tax law change in Jan 2017, where "goodwill" was brought into the Capital Cost Allowance (CCA) regime under Class 14.1. 

Consequently, you will need to report this like your other depreciable assets in the CCA section of your business form.