Am I assuming correctly that the the iptables nat rule IS needed as show in the beginning of item 1 unter "How to start using it?" in the readme or is that simple a reference of how it was done before? To clarify, does the

iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY --on-port <proxyport> \
--tproxy-mark 0x1/0x1

replace the

iptables -t nat -A PREROUTING -j DNAT --to-dest <localip> --to-port <proxyport>