To control accesory decoders without computer, Paco has created a schematic to use switches via the XBUS.
His site contains all the information, but the Eagle and PCB files can be downloaded here.
Note that the RJ11 connector is a type with the clip down (connections on top).
I ordered my PCB’s in China via Elecrow.com. They are cheap, reliable and provide good quality. Normally you’ll get some more PCB’s then ordered. The PCB zip file can be used to order the PCB’s there. Otherwise you can use the eagle files to create your own Gerber files.