yes you can add titles from your PDA. If your scanner (i'm assuming you mean barcode scanner) works with your pda then you can add it that way.

You'll want to sync your collection first and have it sync the entire database  (under recent and upcomming releases (check that option) you'll want to check All. This way all the titles (its very basic info, but something will at least pop up when you put in the UPC) will show on your mobile.

then when you sync back to your desktop it will download the full profile for titles you added.

I notice though that you only have a registered version of the Mobile version. Not sure if it's going to limit your syncing to an unregistered desktop version at all.

-Agrare