Cool!
> I have installed all required package but cannot install the ikiwiki
>
> The Instruction says to install 3.20150107 or newer but that version cannot
> be found and if I try to install from stretch I get the following
>
> -------
> apt-get install -t stretch ikiwiki
I haven't built an ISO myself in a while but I build the website
everyday from Tails 2.0 with the package ikiwiki from testing (3.20150614).
Maybe you can try:
apt install ikiwiki/testing
NB: Beware that '-t testing' and '/testing' do different things :)