component.jar is within the solution.jar
If I understand you correctly, I would say this is the source of your problems. The references in the Class-Path attribute are relative to the location of the JAR file itself. In your case, component.jar should be in the same directory as solution.jar. When deploying the application, the two JARs get bundled up into a single EAR file. Depending on (a) how the application server unbundles the EAR and (b) the application server's classloading mechanism, you might have to do some more work, but this should get you started (assuming I understood you correctly).
Haven't worked with Websphere, but I am sure there must be documentation on their application server's classloader. Another good reference I would recommend highly is chapter 14 of Rod Johnson's excellent "Expert one-on-one J2EE Design and Development".