Question asked and answered on the TRUNK88 forum.
From: Robert Smith
Date: Fri, 6 Jul 2012 17:22:31 -0700
Subject: Re: [TRUNK88] How to use Trunk88 with a Pro97 scanner
Plug in to your headphone jack on the Pro-97 and the sound card on your computer. I have used both the Mic In and Line In and it works on either. Adjust your volume to minimum and slowly increase it watching the signal bar on T88. You will see it starting to come up and the Hex codes start to appear. Adjust it to maximum signal with the signal meter in T88. You will see less and less error in the Hex code beside the signal meter. I am running at 100% using this system. I also have tried it on all of my hand held and base station receivers.