from your question, I would assume you are already trying to coach on the psychology of selling and are less than happy with the results.
If you want your salespeople to be interested in sales psychology enough to learn about it, practice it and adopt it you have to convince them it's in their best interest.
Just like when you are selling to a prospect you have to tune into their channel, WIIFT = What's in it for Them
You need to get across to them that applying sales psychology will get them to make more sales, in less time and have more fun doing it. ... Less stress ... More money to spend on better toys and better vacations.