I'm late to this party but I'll add my bit to maybe help a few with the problem of exposure compensation in Manual mode with Auto ISO.
Gregm61 is correct in saying it is available, as a menu dive, unfortunately for older models it's not a direct button or dial accessible function as Phocal and many others, including me, wish for. It is however still very usable in the circumstances I often find myself shooting in and I make do with what's on offer with the bodies I use. (not EM1 mkII)
I have just copied and pasted an explanation I have supplied in previous posts to explain.
"You are able to exposure compensate in manual mode using auto ISO on most Oly cameras since the EPL1, it's just not instantly adjustable by dial or arrow pad, a menu dive is required. In the "gears" menu then "utility" you will find "exposure shift". This function allows you to override the cameras chosen exposure setting in all three metering modes in 1/6 EV increments. With practice you can access and change the setting within 4 or 5 seconds. I think most of the cameras will remember the last menu you went to so hitting the menu button takes you straight back to the exposure shift function (I don't use the menus for anything else generally because all other settings I may want to change are accessed by direct button).
I use this function a lot with my E5 and EM1 bodies when shooting motorsport, particularly the race boat photography I do. I usually set the E5 to +2/6 to + 4/6 on sunny days to compensate for the cameras desire to under expose the photo because of the amount of white spray generated by the boats. The EM1 is a little better and usually only requires +1/6 to +2/6 although on some of the really bright sunny days we have here in Australia I might have to add a touch more. This would be perfect for shooting in the snow or largely white ice rinks where the camera wants to underexpose."
Now, not ideal I know, as it's not instantly adjustable but for what I'm shooting I don't need to make continual adjustments for every photo. I'm looking for a global change to suit a series of photographs (bursts) in similar conditions. Then I can change it in a couple of seconds when circumstances and conditions change.
Regards Ian Colley