It turned out to be surprisingly simple. Mac OSX /dev/random allows writes and is the recommended method by Apple to seed entropy to PRNG. Therefore, simply creating hourly cron job like this will work as simplistic version for rng-tools on OSX :
send_entropy.sh
#!/bin/zsh
# change Usbmodem to your #
[[ -r /dev/cu.usbmodem14511 ]] && dd if=/dev/cu.usbmodem14511 ibs=1 count=512k obs=1024 >& /dev/null | pv -pterb -s 512k | dd of=/dev/random >& /dev/null
crontab -e
@hourly <path>/send_entropy.sh
.
