For others who may prefer the RegAddBoot approach over using a particular drive letter specified by the script itself, the following substitutions are needed in dera's script.
In the HKU section:
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector","RecoveryExpertPath","%PE_Programs%\%ProgramFolder%\RecoveryExpert.exe"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","fnls.dll","%PE_Programs%\%ProgramFolder%\fnls.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","ftrace.dll","%PE_Programs%\%ProgramFolder%\ftrace.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","icu38.dll","%PE_Programs%\%ProgramFolder%\icu38.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","rpc_client.dll","%PE_Programs%\%ProgramFolder%\rpc_client.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","resource.dll","%PE_Programs%\%ProgramFolder%\resource.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","gc.dll","%PE_Programs%\%ProgramFolder%\gc.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","thread_pool.dll","%PE_Programs%\%ProgramFolder%\thread_pool.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","ntmsapia.dll","%PE_Programs%\%ProgramFolder%\ntmsapia.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","libcrypto9.dll","%PE_Programs%\%ProgramFolder%\libcrypto9.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","libssl9.dll","%PE_Programs%\%ProgramFolder%\libssl9.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","events_trace.dll","%PE_Programs%\%ProgramFolder%\events_trace.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\CommonComponents","core_workers_shared_context.dll","%PE_Programs%\%ProgramFolder%\core_workers_shared_context.dll"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\Settings","WorkingDir","%PE_Programs%\%ProgramFolder%"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\DiskDirector\Settings","SystemInfoPath","%PE_Programs%\%ProgramFolder%\systeminfo.exe"
RegAddBoot,HKLM,0x1,"SOFTWARE\Acronis\WinPE","A43","%PE_Programs%\%ProgramFolder%\A43\A43.exe"
And in the HKLM section:
RegAddBoot,HKLM,0x1,"SYSTEM\ControlSet001\Services\mms","ImagePath","%PE_Programs%\%ProgramFolder%\mmsBundle.dll"
So far as I can determine, when those RegAddBoot items are used, adding the DD11 program folder to the Windows search path is not necessary.