You could add something like this if you want to change subfolder name in just one line of script instead of several lines
Code:
#define Subfolder "System\"
[Setup]
.........
[Icons]
Name: "{group}\{#MyAppName}"; Filename: "{app}\{#Subfolder}{#MyAppExeName}"
Name: "{group}\{cm:UninstallProgram,{#MyAppName}}"; Filename: "{uninstallexe}"
Name: "{commondesktop}\{#MyAppName}"; Filename: "{app}\{#Subfolder}{#MyAppExeName}"; Tasks: desktopicon