You just need to use this method. The important part is setting your referrer (Referring Page) to http://trial.autodesk.com/
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part01.exe
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part02.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part03.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part04.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part05.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_English_Win_32-64bit.part06.rar
This is about 21 gig in total…
i think is missing part6 link?
Here is the link for Navisworks Manage 2013
http://trial.autodesk.com/SWDLDDLM/2013/NAVMAN/ESD/Autodesk_Navisworks_Manage_2013_Multilingual_Win_64bit.exe