Go with Wealth Simple.  They have the T1198 online with their tax service.  Turbo Tax will also force you to go Deluxe probably to do this as well.  Turbo Tax keeps giving the same generic answer blaming CRA, however other platforms have already implemented it.

@chermel27 

The Statement of qualifying retroactive lump-sum payment (T1198) is now available and unlocked in TurboTax Online.

It is available in TurboTax Desktop in Forms mode, but it's still locked. You can see a list of forms that are still in development here: https://turbotax.community.intuit.ca/turbotax-support/en-ca/help-article/tax-return/turbotax-say-for...