The technique is simple. With a 32band EQ i linearized the frequency response slightly. I did not remove all of the typical tone but made the the curve between the resonant frequency and the highest peak more linear.
While this doesn’t look like much you will hear the difference very well.
It is also a big help for solos if there are no great dips and peaks in the IR.
Compared to other techniques like smoothing and so on this will still sound like this particular speaker. Smoothing on the other hand will sound more like old analog frequency corrected d.i. outs of modelers like the sansamp and so on.