[SiRD500YPVS]

Hi to anyone that may be able to help. Basically very new to King's Bounty: The Legend (Version: 1.6.4 / Build: 34,387) - I have physical disabilities and have to use a 3 button trackball, I was wondering how, or if I can use this to get the camera to zoom in (first time I have been made aware I need to do this is with the combination lock puzzle)... can anyone kindly tell me how to get camera zoom in ?
Excuse my ignorance on this, but would truly appreciate any answers / advice.
All the best, Si.