Not sure if you cannot connect to WebSphere7 JMX, or you can connect but do not see your exported MBeans. If it is the latter, I suspect you may be looking at the wrong MBeanServer instance, since WAS technically has more than one running.
Either way, to bypass all that nonsense, your best bet is to add a JMXConnectorServer definition in your Spring XML. That way, you control exactly how the JMX connections should be made, and it will use the standard J2SE RMI remoting, so you know your JConsole will connect to it easily.
Here's an example:
<bean id="MBeanServer"
class="org.helios.jmx.util.MBeanServerFactory" lazy-init="false" factory-method="createMBeanServer">
<constructor-arg type="java.lang.String" value="DefaultDomain" />
</bean>
<bean id="MBeanServerJMXUrl"
class="javax.management.remote.JMXServiceURL" lazy-init="false">
<constructor-arg type="java.lang.String" value="service:jmx:rmi:///jndi/rmi://localhost:8003/jmxrmi" />
</bean>
<bean id="RMIRegistry"
class="java.rmi.registry.LocateRegistry"
lazy-init="false"
factory-method="createRegistry">
<constructor-arg value="8003" />
</bean>
<bean id="MBeanServerConnector"
class="javax.management.remote.JMXConnectorServerFactory"
lazy-init="false"
init-method="start"
factory-method="newJMXConnectorServer"
depends-on="RMIRegistry">
<constructor-arg ref="MBeanServerJMXUrl" />
<constructor-arg>
<map/>
</constructor-arg>
<constructor-arg ref="MBeanServer" />
</bean>