Yes you need a (free) account and have to use the Bulk Download Application.
Problem is that there's no API access to this that I know about unless you get a "special" type of account from USGS
AeroScenery is written to handle ortho tile servers.
Automating high res USGS would require a whole load of screen scraping / HTML DOM parsing / click faking etc.
A compromise might be to let the user download the high res images, select the zips in the app, then let the automation start from there.