Qsys 13.1 tutorial

An SRAM is simple enough that QSYS isn't needed unless you need other components as well. Since you have a custom CPU, you can interface it directly if you write your own code and obey the timing requirements in the data sheet.

If you want to connect to other things on your board that have QSYS components ready to go you should consider QSYS. It wouldn't be difficult to create a custom QSYS component to house your CPU. Just expose an Avalon or AXI master interface and create a connection to the SRAM in the example you've sited. You could for example use a UART component to connect to the DB9 or USB based RS232 port found on some boards to give yourself a console. Most dev boards have flash you could use as well.