Good luck Julian, my engineer friends ask me about converting at least once a week. Not until there is a $1000 plan available and a schematic to follow will I be able to justify the effort. Unfortunately, Toyota may beat that to the punch with their own solution.

Pardon me, but so far there are THREE options in North America, not two:
1) Hybrids Plus http://hybrids-plus.com/
2) EnegyCS / EDrive
3) HyMotion
And more are coming...