The whole point of using older drum machines is to capture that crunchy sound. Midi cant help there. You have to plug the output into a DI.
If its a stereo drum machine, and you have a stereo mic pre with 2 DIs, plug it in there and mess around with the gain and output on the mic pre until you get a nice sound. Also, a compressor or EQ can help get the sound there quickly on the way in.
My favorite units for this trick is are:
1) Vintech 473 --> Fatso
2) Langevin DVC
Although going straight into the inputs on your audio interface and using plug ins is an option, it probably wont sound as good as using some hardware upfront first.