Group Policy

No, it's not. But why would you want that?

If that is the case, you can scope your GPO by using an WMI filter:

SELECT * FROM Win32_ComputerSystem WHERE Name = 'MyComputer'

So that the policy will only apply to the computer named MyComputer. You can use OR to include additional computer names:

SELECT * FROM Win32_ComputerSystem WHERE Name = 'MyComputer' or Name='MyComputer2'

and so on.

just found:

https://www.experts-exchange.com/questions/23602124/IE-Proxy-settings-group-policy-at-computer-level-not-user.html

Have you tried with GPO Loopback processing?
http://support.microsoft.com/kb/231287

Regards,
Krzysztof

Hi HI-LTD. This can be easily done by making the changes you need via script; and then push the script via Computer Config on the GPO. The IE Proxy settings are located at:
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"ProxyServer"="<your proxy IP address>:8080"
"ProxyEnable"=dword:00000001
"ProxyOverride"="<local>"

Then use REGEDIT in the login script to push the settings to the workstations:
#Regedit /s z:\public\setpxy.reg
Of course this depends on what language your using for your logon scripts.

Good luck!

went the route of movign the policies around and not use loopback