test.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:access_control_1_0="http://berlinonline.de/schemas/honeybee/config/access_control/1.0"
    targetNamespace="http://agavi.org/agavi/config/global/envelope/1.0"
    elementFormDefault="qualified"
>

    <xs:import namespace="http://berlinonline.de/schemas/honeybee/config/access_control/1.0"
        schemaLocation="parts/access_control.xsd" />

    <!-- <xs:redefine schemaLocation="%core.agavi_dir%/src/config/xsd/_envelope.xsd" -->
    <xs:redefine schemaLocation="../../../vendor/agavi/agavi/src/config/xsd/_envelope.xsd"
        xmlns:acl="http://berlinonline.de/schemas/honeybee/config/access_control/1.0">
        <xs:complexType name="configuration">
            <xs:complexContent>
                <xs:extension base="configuration">
                    <xs:group ref="access_control_1_0:configuration" />
                </xs:extension>
            </xs:complexContent>
        </xs:complexType>
    </xs:redefine>

</xs:schema>

test.xsl

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
    version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>
    <xsl:output method="xml" version="1.0" encoding="utf-8" indent="yes" />

    <xsl:variable name="in">../../../vendor/agavi/agavi/src/config/xsd/_envelope.xsd</xsl:variable>
    <xsl:variable name="out">../../../../../../vendor/agavi/agavi/src/config/xsd/_envelope.xsd</xsl:variable>

    <xsl:template match="@* | node()">
        <xsl:copy>
            <xsl:apply-templates select="@* | node()"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="@schemaLocation[starts-with(., '../../../')]">
        <xsl:attribute name="schemaLocation">
            <xsl:value-of select="translate(., $in, $out)"/>
        </xsl:attribute>
    </xsl:template>

</xsl:stylesheet>