I believe with FF4 those commands are obsolete (I don't know for sure about the "-safe-mode" though), but you can check here on why, and how-to manage profiles with the new manager:
http://www.ghacks.net/2011/01/19/firefox-profile-manager-to-be-removed-soon/I've tried the new one (v1.0_beta2) for a week now, and the program is still in development, so expect no frills, and just a few more options than the first very bare one. Not very documented (by Mozilla) either, so hit above link for screenshots, how-to and link to download.
I didn't get great results with the backup and restore options (took ages, didn't do all that I wanted), so for backups/restoresI keep on using MozBackup (that always has been pretty reliable to me).