This should be doable via overriding (copying) the connection factory bean in your project applicationContext.xml
<bean id="terminalConnectionFactory" class="org.openlegacy.providers.tn5250j.Tn5250jTerminalConnectionFactory" p:waitTimeout="10000" p:waitPauses="300">
<property name="properties">
<props>
<prop key="SESSION_HOST_PORT">${host.port}</prop>
<prop key="SESSION_CODE_PAGE">${host.codePage}</prop>
<prop key="SESSION_TN_ENHANCED">true</prop>
<prop key="-sslType">SSLv2 OR SSLv3 OR TLS</prop>
</props>
</property>
</bean>