I know you've decided to move on and get a trunking scanner, but the original question was a good one that deserves a full discussion for future reference.
Analog trunking systems can be monitored with a radio that does not trunk track. However, monitoring them and effectively scanning them are two different things. Everytime someone transmits on that system, they will come up on a different frequency of the system. So, almost everytime they unkey their microphone, you're going to have to start quickly running through every frequency in the system to catch the rest of the conversation. In a small town, 5 frequency system that is not shared by all the dog catchers, sewer workers, water works, street pavers, traffic signal techs, park lawn mowers, ambulance drivers, and firemen in the city, it's not a completely overwhelming task, but certainly a pain in the arse. You'll miss a great deal of things you were trying to hear. You won't even know who you are listening to (what channel) unless you recognise the voices, unit numbers, or locations.
If your system consists of ten or twenty frequencies, forget it. You could scan them with a conventional scanner and get the general gist of things, but again, you're still not going to be able to effectively follow entire conversations. Nor will you be able to separate fire, EMS, police, and public works from each other. With a modified ham HT, the scan mode is simply way too slow to even do that much.
So yeah, you can monitor the individual frequencies, but no, you can't effectively scan the system as a whole.
Thanks to Uniden and UPman, here's a link that will help you understand why. Looking forward to see what you end up buying!