You may use this on main branch! (Network>VPN>EoIP)

OpenWRT Package to compiler Ethernet Over IP (v0.5), is compatible with Mikrotik.

Use software from http://linux-eoip.googlecode.com/files/

For compile

Download repository
Place linux-eoip directory to openwrt/package/network/services/
Run make menuconfig
Select packet on Network
If you need Luci web interface see https://github.com/bogdik/luci-app-eoip