OT: moving instruments in a finished 2bus recording

["Rainer Thelonius Balthasar Straschill" <rs@moinlabs.de>]

Again hoping do dig something up in this huge ball of know-how:

I have this performance recording (stereo recording) where due to some 
setup
mistake the entire drumset, instead of spanning L to R, is panned C to R.
Which means (among other unpleasant things) that the bassdrum comes to sit
about 50% to the right.

What I want to do:
Move the drums (well, especially the bassdrum is important) to roughly
center without
        a) making one channel a lot louder than the other
        b) loosing mono compatibility
        c) completely collapsing the stereo image
        d) moving everythin that was center to hard left (or something
radical)

Other strange and unwanted effects wouldn't pose a problem, though.

Is this possible?

        Rainer