libraries/ManiaLib/Application/Tracking/GoogleAnalytics.php
function getEventTrackingURL($category, $action, $label, $value = null)
    {
        $this->utme = sprintf('5(%s*%s*%s)', $category, $action, $label);
        if ($value !== null) {
            $this->utme .= sprintf('(%d)', $value);
        }

        $params = array(
            'utmwv' => $this->utmwv,
            //'utms' => null ?
            'utmn' => $this->utmn,
            'utmhn' => $this->utmhn,
            'utmt' => 'event',
            'utme' => $this->utme,
            'utmcs' => $this->utmcs,
            'utmsr' => $this->utmsr,
            //'utmvp' => $this->utmvp, view port resolution
            'utmsc' => $this->utmsc,
            'utmul' => $this->utmul,
            'utmje' => $this->utmje,
            'utmfl' => $this->utmfl,
            'utmdt' => $this->utmdt,
            'utmhid' => $this->utmhid,
            'utmr' => $this->utmr,
            'utmp' => $this->utmp,
            'utmac' => $this->utmac,
            'utmcc' =>
                '__utma=' . $this->__utma . '+' .
//					'__utmb='.$this->__utmb.'+'.
//					'__utmc='.$this->__utmc.'+'.
                '__utmz=' . $this->__utmz,
        );

        return self::GA_TRACKING_URL . '?' . http_build_query($params);
    }
function getEventTrackingURL($category, $action, $label, $value = null)
    {
        $this->utme = sprintf('5(%s*%s*%s)', $category, $action, $label);
        if ($value !== null) {
            $this->utme .= sprintf('(%d)', $value);
        }

        $params = array(
            'utmwv' => $this->utmwv,
            //'utms' => null ?
            'utmn' => $this->utmn,
            'utmhn' => $this->utmhn,
            'utmt' => 'event',
            'utme' => $this->utme,
            'utmcs' => $this->utmcs,
            'utmsr' => $this->utmsr,
            //'utmvp' => $this->utmvp, view port resolution
            'utmsc' => $this->utmsc,
            'utmul' => $this->utmul,
            'utmje' => $this->utmje,
            'utmfl' => $this->utmfl,
            'utmdt' => $this->utmdt,
            'utmhid' => $this->utmhid,
            'utmr' => $this->utmr,
            'utmp' => $this->utmp,
            'utmac' => $this->utmac,
            'utmcc' =>
                '__utma=' . $this->__utma . '+' .
//					'__utmb='.$this->__utmb.'+'.
//					'__utmc='.$this->__utmc.'+'.
                '__utmz=' . $this->__utmz,
        );

        return self::GA_TRACKING_URL . '?' . http_build_query($params);
    }
Experimentation about using Event Tracking in manialinks.
Because I don't know the exact algorithm to encode data in utme, you should
only use alphanumeric chars in the parameters for now.
To quote official doc: "Value is encoded. Used for events and custom variables."

@see https://developers.google.com/analytics/resources/articles/gaTrackingTroubleshooting#gifParameters
@beta