First the failure mode (for contrast):
PMM does a kick ass job with product decks and slicks. There is a training session where some people seem to be paying attention, but most people are distracted by their day-to-day job of sales. Then when a sales person gets an opportunity, they ask the PMM or PM to come in and help. Or worse, the sales lead complains at the company QBR that her team is not enabled properly.
What I think is better:
Start with what's in it for the sales person... Is it higher deal value to satisfy quota? Higher win rate?
Then, think through how your sales people will sell the new product... will the SE go and do a demo during the next customer QBR? Will they be able to talk about a broader company story during the next renewal or new customer negotiation? How will they price the new deal with the new product in there?
Then work backwards from there to figure out what assets are required. Often I find that pricing proposals, an updated company/platform story, demos are critical.
Regardless, the key is to have your best sales person (someone everyone in Sales considers to be the best amongst them), to get up on stage and talk about how she will sell the new product. That means, your job is to work with that person and prep her with the right information and assets.
You never want a marketing or product person to tell how a sales person should do their job. Instant credibility loss and guards come up. Just like you hate a Sales or Product person telling you how to do Marketing.