(note: I have never used/experienced the system you're referring to)
There are two parts to the woe ranking system:
1. src writes SQL data when certain actions take place.
E.g. when a player kills somebody, perhaps the src would add 1 to kill_counter row.
2. Website has some sort of interaction with the game SQL database to display the data graphically.
Lucky for you, eAmod became open source some time ago. You can view the SQL info here: https://github.com/zephyrus-cr/eamod/blob/master/sql-addons/main-extras_eAthena.sql
A sample of what is happening in the SQL:
CREATE TABLE `guild_rank` (
`guild_id` int(11) NOT NULL,
`castle_id` int(11) NOT NULL,
`capture` int(11) unsigned NOT NULL default '0',
`emperium` int(11) unsigned NOT NULL default '0',
`treasure` int(11) unsigned NOT NULL default '0',
`top_eco` int(11) unsigned NOT NULL default '0',
`top_def` int(11) unsigned NOT NULL default '0',
`invest_eco` int(11) unsigned NOT NULL default '0',
`invest_def` int(11) unsigned NOT NULL default '0',
`offensive_score` int(11) unsigned NOT NULL default '0',
`defensive_score` int(11) unsigned NOT NULL default '0',
`posesion_time` int(11) unsigned NOT NULL default '0',
`zeny_eco` int(11) unsigned NOT NULL default '0',
`zeny_def` int(11) unsigned NOT NULL default '0',
`skill_battleorder` int(11) unsigned NOT NULL default '0',
`skill_regeneration` int(11) unsigned NOT NULL default '0',
`skill_restore` int(11) unsigned NOT NULL default '0',
`skill_emergencycall` int(11) unsigned NOT NULL default '0',
`off_kill` int(11) unsigned NOT NULL default '0',
`off_death` int(11) unsigned NOT NULL default '0',
`def_kill` int(11) unsigned NOT NULL default '0',
`def_death` int(11) unsigned NOT NULL default '0',
`ext_kill` int(11) unsigned NOT NULL default '0',
`ext_death` int(11) unsigned NOT NULL default '0',
`ali_kill` int(11) unsigned NOT NULL default '0',
`ali_death` int(11) unsigned NOT NULL default '0',
PRIMARY KEY (`guild_id`,`castle_id`),
KEY `castle_id` (`castle_id`)
) ENGINE=InnoDB;
And then by searching the src repo, you can find snippets of the code.
This quite complicated. To recreate it to work for Hercules would take a lot of work. of course you could just use Zephyrus' HercMod but I really don't recommend doing that.