Altiverb gives you separate controls for both ER and Tail (gain and delay). I haven't used TL Space in a while but I believe that also provides separate controls for those parameters. These processes are obviously done post-IR conversion; I don't know of a method of stripping the ER out from the longer reverberation before using the IR in a convolution plug-in.
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Im with Jay - but this plug-in might do something you would like:
First do the deconvolution of the input impulse and the recorded room response. This will give you the IR file for the room. (You could do this in Matlab, but you'll need some background to use it. Logic comes with an app called IR Utility that will do the deconvolution assuming the response recording was done with an input sine sweep.) Save the IR file and open it in any wave editor so you can edit the file. Then remove the IRs "tails" (diffuse field) either by cutting or fading. This will leave just the direct sound and the early reflections. (The point you do the the cut/fade will affect the results so you may want to play around a bit, depending on what you are trying to achieve.) Save the modified IR and open/apply it using your preferred convolution reverb.