Go toby for scoring some new gear!
If he has had any farrier work done, it should be easy to get around him and get them on. You can expect him to high step around a bit if he has never worn them. That's normal though and he'll quit pretty quickly.
Are they velcro like the SMB's over at Professional's Choice - Protective Gear - SMBE
Or leather like the splint boots over at https://www.edgalemba.com/sesamoidsplintbootdetail.php
The reason I ask is because you need to be careful when removing them if they're velcro and he has never had them on before. The sound can sometimes scare horses.
Have fun with your new stuff!