EDIT:
I paste here the instructions from the user @katerpanne :
0. Use "MI8 TWRP" on "MI8 Explorer Edition" and install custom ROM
1. open downloaded custom "rom.zip"
2. go to -> \xiaomi.eu_multi_MI8Explorer_V10.0.4.0.OEHCNFH_v10-8.1.zip\META-INF\com\google\android\
3. edit -> updater-script
4. change -> getprop("ro.product.device") == "ursa" to getprop("ro.product.device") == "dipper"
5. enjoy