Two versions are available here for download in one package.
The default RiscLua 8 requires an ARM processor with VFP, and so is not suitable for RiscPC or Iyonix. If you drag the !rlua8 directory inside the IYO directory on top of the default version, it should run on the Iyonix - maybe even the RiscPC. This version has the lpeg and riscos libraries built in. Its arithmetic uses 32bit integers and 32bit VFP floats (32 bit soft floats for the IYO version). It is based on Lua 5.4.0(alpha), which has some experimental new features which may or may not survive into the beta version.