Attempted - still getting "151: HTTP protocol error. 400 Bad Request." I'm just trying to query some FI Profile info, and using the anonymous password (plus 0s), but even when using my actual account info, I'm still getting this error. I saw another list providing a separate website for T. Rowe Price brokerage stuff and FI_Org was just TRP, but I gave that a try and got the same result also. Will keep playing with it.
Of note, I was able to get into the brokerage using T. Rowe Price's Brokerage address, which is separate from regular T. Rowe Price.
Supports anonymous Signon for the Info Request.