I tried it without a password and it didn't work. I tried to try to create a kiosk account for my windows pc. I launched it automatically from the commandline C:\Program Files\VMware\VMware View\Client\bin\wswc -unattended -password Secret -serverurl cscviewconnsrv.usadir.usa.usouthal.edu and that did work and it did log in with the kiosk account. And in the connection server log it showed the domain in front of the user name for the windows pc, but I don't see that for the thin clients.
Here is part of the log of the connection server
2014-12-30T11:53:20.555-06:00 WARN (0768-1618) <MessageFrameWorkDispatch> [ws_winauth] LogonUser FAILED, error=1326 (Logon failure: unknown user name or bad password.) {SESSION:b581_***_26a0; cm-00_80_64_b2_1b_41}
2014-12-30T11:53:21.566-06:00 INFO (0BF4-1358) <TP-Processor8> [WinAuthFilter] (SESSION:38f8_***_1bc2 cm-00_80_64_b2_19_ac) User \cm-00_80_64_b2_19_ac has failed to authenticate to VDM
2014-12-30T11:53:24.287-06:00 WARN (0BF4-100C) <TP-Processor1> [ClientAuthFilter] (SESSION:ee7a_***_7bcc) Client Authentication for client cm-00_80_64_b2_19_ac will fail due to missing domain setting
2014-12-30T11:53:24.295-06:00 WARN (0768-1618) <MessageFrameWorkDispatch> [ws_winauth] LogonUser FAILED, error=1326 (Logon failure: unknown user name or bad password.) {SESSION:ee7a_***_7bcc; cm-00_80_64_b2_19_ac}
2014-12-30T11:53:26.346-06:00 WARN (0BF4-17E4) <TP-Processor6> [ClientAuthFilter] (SESSION:ab41_***_6715) Client Authentication for client cm-00_80_64_b2_18_3f will fail due to missing domain setting
2014-12-30T11:53:26.363-06:00 WARN (0768-0568) <MessageFrameWorkDispatch> [ws_winauth] LogonUser FAILED, error=1326 (Logon failure: unknown user name or bad password.) {SESSION:ab41_***_6715; cm-00_80_64_b2_18_3f}
2014-12-30T11:53:27.645-06:00 WARN (0BF4-1360) <TP-Processor5> [ClientAuthFilter] (SESSION:da10_***_3596) Client Authentication for client cm-00_80_64_b2_16_c2 will fail due to missing domain setting
2014-12-30T11:53:27.653-06:00 WARN (0768-1618) <MessageFrameWorkDispatch> [ws_winauth] LogonUser FAILED, error=1326 (Logon failure: unknown user name or bad password.) {SESSION:da10_***_3596; cm-00_80_64_b2_16_c2}
Note that there isn't anything after the word User and before the \.
There isn't anywhere on the P25 to specify the domain name in the View Connection Server + Kiosk Mode