What are you trying to do in the end? Are you trying to set the resolution in WinPE during deployment, or set the resolution of a Windows 7 image that you just put down?
Setting it in WinPE: https://technet.microsoft.com/en-us/library/ff716217.aspx
Setting it in deployed Windows Image: https://technet.microsoft.com/en-us/library/ff715801.aspx
If the machine is already imaged and you are trying to do it as part of some SWD task or something, then I'm not sure. Hopefully the above should help. You can set it in the unattend.xml file and use Provisioning to inject that unattend file.
If it is working outside provisioning you could use startasuser.exe to run qres.exe with the current user.
If your OS is 64bit you should know that provisioning is a 32bit application and all applications are started as 32bit. In some situations it is necessary to start in 64bit. To start in 64bit you could start cmd.exe via "c:\windows\sysnative\cmd.exe /c c:\qres.exe"