You can transpose minor chords in the same way that you transpose major chords, or any other type chord for that matter. But some people misunderstand the the whole idea of transposing.
Transposing means that you are changing the actual key of a song. It means that a series of chords in a progression will become a whole new series of chords in a new progression.
It doesn’t matter at all if the chord that you are changing is major or minor, a 7th cord, a 6th chord, a sus4 chord or any chord. Major transposes to major, minor tto minor, 7th to 7th etc. You can use the chromatic scale to effect the transposition.
For example, if we have a chord progression that goes like this:
A D Em A D Esus4 A
This progression is in the key of A, but if we want to transpose this to the key of C we will end up with:
C F Gm C F Gsus4 C
THis is done by direct up down substitution by using two chromatic scales one starting with A, and another starting with C. I can do this because I can start the chromatic scake from any note I choose. The chromatic scale is theoretically a never ending scale.
A– A#/Bb– B– C– C#/Db– D– D#/Eb– E– F– F#/Gb– G– G#/Ab– A
C- C#/Db– D –D#/Eb -E—- F– F#/Gb– G- G#/Ab- A— A#/Bb- B—- C
The point is that you are doing letter to letter substitution. It doesn’t matter at all what type of chord it is. The type goes along for the ride. Always.
Here’s another misunderstanding: Chords do not change when you change keys. A G chord is a G chord no matter what key you are playing in. An Em is an Em is an Em is an Em. Always.
Chords have specific definitions that have nothing to do with what key they may be played in. A G chord will always be made up of a G a B, and a D. This by definition IS a G chord.
To sum up, transposing is not a mysterious concept. It is logical. If you understand the chromatic scale you can do it easily. You don’t need any charts or special rulers or 50 pages of music theory.
Don’t allow chord types to bother you when you’re transposing. The types remain the same across keys.
Lastly, the definition of what makes up an individual chord will never change no matter what key you are plaing in.