And this forum is for official DOSBox. Besides, Daum is broken.

Many things in this world are "possible".

Rather than asking about what is "possible", perhaps you can provide an example of something specific you'd like to run that you know would benefit from MMX emulation? Or are you only interested in throwing out random questions?

Impulse Tracker 2.x. Requires MMX for real time resonant filters, or can render them using floating point instructions at sub real time, in mono if you weren't one of the l33t scene kids who sent Jeffrey Lim money back in the day for the super special stereo wav writer.

Extreme Assault. Both a DOS and Windows 9x game. Requires MMX for software rendered 3D graphics with color and alpha blending effects. Maybe not such an incentive since there's probably also a Voodoo graphics hardware rendering version, but I wouldn't be surprised if they used MMX in that renderer as well.

Other than that, I got nothing.

Armored Fist 2 is a dos game that uses MMX pretty heavily

More of the gamut of MMX games are on Windows 9x which aren't relevant for DOSbox here. POD, Rebel Moon Rising, etc

There's also the world of emulators that uses MMX heavily, such as ZSNES (which is really craving MMX for sound mixing, and between a Pentium and a Pentium MMX the performance difference is like night and day)