The question says it all. I see some tutorials online for earlier editions of Ubuntu, but am having a hard time for 12.04.
There is generally no need to adjust IRQ priority unless you are having particular problems and want to apply boot options such as
However, you are probably referring to the hwtools package that was available before even Hardy (8.04) and which contained the
However, there is a program in the repositories called irqbalance, which is designed only for multi-core CPUS. There is more information here, but it may not be appropriate for you as it is more to do with balancing server load.
If you want to list your IRQ ports in Ubuntu you can run