you will need:
crystax ndk
http://www.crystax.net/android/ndk-r4.php
download and unzip to your home directory

run the getvtk.sh script, or download and unzip VTK release 5.6.1 somewhere.

then from this directory:
mkdir build
cd build
cmake-gui ..
make

As part of the cmake-gui step, select the VTK root directory ( if its different ), and the android-ndk path.
you may want to set j to 16 or something.