If you start the VI client from the command prompt or with a shortcut, you can add several options to bypass the login screen. If you're using vCenter server you can use --usePassthroughAuth and --server to login to your vCenter server. Instead of --server you can also use the -s option.
C:\Program Files\VMware\Infrastructure\Virtual Infrastructure Client\Launcher>vp xclient --PassthroughAuth --server <vCenter_hostname_or_IP>
If you connect to a standalone ESXi host, you can specify the host, login and password to use.
C:\Program Files\VMware\Infrastructure\Virtual Infrastructure Client\Launcher>vp xclient --user root --password secret --server ESX01
C:\Program Files\VMware\Infrastructure\Virtual Infrastructure Client\Launcher>vp
xclient -u root -p secret -s ESX01
Copyright © 2009 - Dave Mishchenko