You should be able to automate the process with a heat-gun by wiring its element through a ramp/soak controller, with inputs taken either from the airstream or from the bean mass itself. If you search here and on homeroasters.org, you should be able to find a few examples of similar set-ups that you could use as inspiration.

Like Gary, I use mine with manual control over heat & fan (I bought a cheap heat gun and wired its element into a dimmer switch), and digital monitoring of temperatures. I find the process of tweaking a roast in progress to match a planned profile to be very enjoyable, both on my HG/BM and on my drum roaster, so I have never felt much urge to automate the controls.

FYI, even if you automate the roast, you'll still want to be on hand to monitor it in case something goes wrong. Fire is a real risk in this hobby, and equipment does not always function as intended. I figure you probably already realized this, but I wanted to remind you, just in case.