Doesn't the offline mission planner have that info?
And for a while things were cold,
They were scared down in their holes
The forest that once was green
Was colored black by those killing machines
Solution; wait till I15, when level ranges will be able to be set by the mission creator.
I don't fancy waiting another month to make something I want to run tomorrow.
And the offline mission planner doesn't have easy cross-referencing.
Perhaps the paragonwiki has enemy groups sorted by level range somewhere?
Winner of Players' Choice Best Villainous Arc 2010: Fear and Loathing on Striga; ID #350522
or you could login and make your own.
*shrugs* just sayin'
I guess you missed where he said that he had computer issues and wanted to do this without logging in.
Winner of Players' Choice Best Villainous Arc 2010: Fear and Loathing on Striga; ID #350522
I understood him to say he would be stealing time to look it up without a list. I'm suggesting he steal time once to make his own list, assuming no one else has done it.
To the op - My apologies if you are completely unable to login and are writing up a mission to pass the time. Sorry.
It's okay.
I was actually writing out the mission arc on paper. A notepad. On the bus. 
I do the same, well, not on a bus but at a table during lunch. I find it helps to get at least an outline on paper before I start.
I leave the enemy group off with perhaps a vague level range or type of group I want then look it up later.
Some missions of course are made for certain groups but in that case you wouldn't care about levels. 
I don't suppose some enterprising individual out there has already created a resource whereby we can look at enemy groups across level ranges? I'm currently trying to do planning for an arc without using the game itself much (computer issues) and was wondering if I'd have to keep stealing time to find which enemy groups can give me the forced level range I want.