The Boot Disk Creator does not offer Powershell as an optional component to inject in to the WinPE environment and you would like to add this.
The use of Powershell in WinPE is outside the scope of Ghost Solution and not supported by Symantec. You can add Powershell manually to your existing boot.wim using information from Microsoft. The following article contains instructions for mounting a WIM image, injecting the components in to the boot.wim necessary for the Powershell components.
Please note that the above link to Microsoft information may change at any time. Contact Microsoft for more information or if the information has moved.