inotifywatch may help. Packaged in inotify-tools.
Use as the user of files/dir for home dir being watched, not sudo, or you'll get errors on .gvfs if running a newer gnome.
inotify will only tell you which files get accessed/created/modified/deleted.
$ inotifywatch -r /home/username/.* /home/username/*
Establishing watches...
in another terminal
$ cat /home/username/.bashrc
in inotifywatch terminal ctrl-c to end
Finished establishing watches, now collecting statistics.
total access modify close_nowrite open filename
3 1 0 1 1 /home/username/.bashrc
For your specific request, all files accessed during login.
$ inotifywatch -r /home/username/.* /home/username/*
Establishing watches...
in another terminal
$ sudo su
# login username
in inotifywatch terminal ctrl-c to end
You may want to redirect the inotifywatch to a file if using a fat desktop like gnome or kde. Or increase your scrollback in the inotifywatch terminal. In gnome 3, thousands of homedir files are accessed during login. You'll probably want to either exclude directories or make a specific dir/file list to watch.