I'm afraid, according to the About the Wireless Hosted Network on Microsoft Dev center, this is not possible.
To provide protection for the wireless communications between the computer hosting SoftAP and the devices connecting to the SoftAP, the wireless Hosted Network requires that all devices connected use the WPA2-PSK/AES cipher suite.
The shared key is a 63-character value generated by Windows when the wireless Hosted Network is invoked for the first time. This primary key is called the "system security key" in netsh wlan commands.
To allow for ease of use, wireless Hosted Network also supports the concept of a secondary or user security key that is more user-friendly, but could be less secure. This secondary key is called the "user security key" in netsh wlan commands.
The secondary key is not generated by Windows. The user must supply the value for this key. A user or application may set or change the key value by calling the WlanHostedNetworkSetSecondaryKey function or by using the netsh wlan commands. The secondary key can be set to be persistent or temporary. For a temporary key, if the wireless Hosted Network is already running, the secondary key will be valid until the wireless Hosted Network stops. For a temporary key, if the wireless Hosted Network is not running, it will be valid only between the next wireless Hosted Network start and stop.