For disassembly, see the dell site. For example on Inspiron 2200 look here:http://support.dell.com/support/edocs/systems/ins2200/
Once you get it apart you are on your own. Theoretically it should be easy, unsolder the old jack, procure the correct replacement jack, solder it to the board. Test and install.
I tried a board level repair but without the right tools, knowledge and experience it can be tough. Both my experiences ended in replacing the motherboard.