Jay, Discovery Mode is indeed in the Extreme options.
To achieve the desired result here, I may have to use your suggestion of a rediculously long frequency list in Sentinel.
I need to play with Sentinel some more, hopefully there is some way to automate this process, if at least a little bit. Direct frequency entry works ok, but still extremely tedious.
EDIT: Researching 3rd party software. Looks possible that other software may be able to automatically "build" me a list that forces a scan of a designated range.
If you want to make a "scan list" of a range, for entry into a Favorites list, open up Excel and type in the lowest frequency into say cell A1, then in A2 type in a formula like:
=A1+.0125
or whatever the proper step is for the band you're wanting to search.
Copy cell A2 into A3 thru Awhatever-you-want, then copy cells A1 to Awhatever-you-want into the Favorites List Editor in a new favorites list/system/department. So long as you have one blank channel to paste into, the Favorites List Editor will expand the channels to fit however many you need. Just make sure you're in the actual Favorites List Editor and not just Sentinel. (Hit Ctrl+2 when you're in Sentinel, to enter the Favorites List Editor.)
You'll probably want to paste your frequencies into both the Frequency and Channel Name fields. That way, you'll know what frequency you hit on if you get one.
If you have no choice but to do a search this way, that's the best way to put it together. Far better than typing it in manually into either Sentinel (the FLE) or the scanner itself.