In our lab setups, we typically require several kinds of RJ-45 connections: rollover (Console), Ethernet crossover (X-over), and standard Ethernet straight-through cabling. For a reminder of the pin assignments, check Cisco.com (http://www.cisco.com/univercd/cc/td/doc/product/access/acs_mod/cis3600/hw_inst/cabling/marcabl.htm).
Serial X-over cables are an entirely different matter due to the variety of interfaces. Again, refer to Cisco.com for details. Optical PCI ATM adapters can be connected back to back via a simple optical X-over cable pair without the need for an ATM switch. However, you will not be able to test network-to-network interface (NNI), switched virtual circuit (SVC), or interim local management interface (ILMI) features without an intermediary switch.