Can I access aTV system files with WinSCP ?

I purchased ATV flash a couple days ago (3.2.3 I think) and borrowed a mac to reflash my Apple “take 2” unit. The aTV now see’s my external 1TB drive and I can dump files to it with WinSCP. There are a number of directories in the aTV root (“atvflash”, “Documents”, “Jaman”, …) but none of the “system/” directories that a number of the postings here reference. Can I get at these directories to view/edit/rename aTV files using the WinSCP GUI on my windows machine ? My unix exposure is light and very stale.

I mainly interested in getting my massive video library of home movies (some 150 hrs) and digital photos over to the aTV for easy ATV_FLASH access. Is there some place on the aTV to put movie poster images for display during movie clip selection on the aTV?

Also- I tried the WinSCP terminal program and get nothing but “500 unknown command” errors. I managed an aTV connection after playing with “putty.exe” and “puttygen.exe” but have had no luck with the WinSCP terminal program.