Mark2 comes with a special release of Tinkergnome's firmware. This adds the extra magic to the tool changer. In fact, the entire, asymmetric hardware setup simply wouldn't be feasible without firmware-integrated tool changing, z-offset handling and much more.
The intention of the firmware extensions is that every task for the magnetic tool changing can be handled by the firmware.
There's no need for specific slicer plugins (or similar things).
Download the Mark2 firmware from github. Connect you printer via USB. In Cura, select "Manage printers" -> "Upgrade firmware" -> "Upload custom firmware". The Mark2 firmware comes in standard or Tinker flavor, select what you prefer. After rebooting you should have access to the "Dual extrusion" menu in "Maintenance" -> "Advanced".
The Mark2-firmware has built-in scripts for z-offset, tool change and wipe.
The wiper is not yet available (but probably coming soon), please switch it off here (for the moment).
Switch between extruders (for testing and calibration)
Configure the retract length, speed and extra priming amount for both extruders.
These settings interfere with the similar options from the slicer. The firmware tries to take care of it, at least it should work together with Cura and Simplify3D. Reports from other slicers are welcome.
X/Y/Z-offset of the second extruder.
X/Y can be adjusted with absolute values or with the matching line number from the calibration print.
More about this at the calibration topic.
The position where to "pick-up" the second toolhead.
The "MOVE" option allows to move (and adjust) the printhead position on the fly. Again - more about this at the calibration topic.
The start position for the wiper. Just ignore it for the moment...
Adjust the z-position of the active extruder. It works similar to the buildplate wizard, but with a simple "one touch and store".
Use the "Change extruder" function to switch between extruders and calibrate the z position for both.
This should be only needed once in the beginning, or after a buildplate re-leveling or nozzle change.
If you want to use the normal buildplate leveling procedure please take care to switch to extruder number one first...
Toolchange retraction settings and the extruder offsets are available during a print as additional "TUNE"-options.
The temperatures are not longer tuned by absolute values, but by an relative offset to the predetermined values (+- 25 degrees).
That's the same as on the Ultimaker 3 and ensures, that we can use the benefits of the "temperature magic" generated by Cura.
For gcode files without additional temperature commands the Mark2-firmware reduces the temperature of the inactive nozzle after a certain amount of time (until the next tool change).
Download the config files for Cura from github. The directory structure matches the "resources" directory in the Cura package (except for "scripts" which translates to "plugins / plugins / PostProcessingPlugin / scripts"). Exit Cura and copy all files to their respective directories within the Cura package. Launch Cura again. Goto "Settings / printer / Add printer". There you should find a new entry labelled "Ultimaker Mark2".