There already is an idlelib/idle.bat that starts the corresponding python with

set CURRDIR=%~dp0
start "IDLE" "%CURRDIR%..\..\pythonw.exe" "%CURRDIR%idle.pyw" %1 %2 %3 %4 %5 %6 %7 %8 %9

Arguments added to the .bat command are passed on. So the enhancement requested already exists.

C:\Programs>python34\lib\idlelib\idle.bat, for instance, starts 3.4, and changing '34' to '33' or '27' starts 3.3 or 2.7.

python -E ignores PYTHON* environment variables. Unfortunately, this seems to prevent python from running idle. Adding -E to the above or directly to
C:\Programs\Python34>pythonw.exe Lib/idlelib/idle.pyw -E
results in a new prompts with no visible action. Since I do not have any PYTHON* vars to ignore, this puzzle me. Does this indicate a bug in the startup handling of -E? (Nick?)

Except for this puzzle, I would close this as a third party issue.