Im not sure if you could do this with just a shortcut.
You can start the first process with a high priority with a line like....
c:\WINDOWS\System32\cmd.exe /c start "runhigh" /high "C:\Documents and Settings\Admin\Local Settings\Application Data\Google\Chrome\Application\chrome.exe"
...but this will only start the original process in high priority (although that may work for you?)
Otherwise your going to have to use an app like (first/only one i tried)....
....go to Configure.. and turn off Tame Applications Based on CPU Usage and then set a rule for Chrome and all processes will be what you set