I suggest you:
1. Learn Ruby. Google for plenty of resources.
2. Learn UNO, and whatever APIs it provides for extension (e.g. C function
calls, SOAP interface or whatever). If necessary, learn C, SOAP etc.
3. Write some code to get Ruby to talk to UNO.
4. When you get stuck on a specific problem, ask for help with that
Also, search for interfaces in other scripting languages (e.g. existing
bindings from Perl, Python or TCL to UNO). That may give you clues on how to
go about it. If these don't exist, then you probably need to ask on an UNO
mailing list, not a Ruby one, about how to go about this. Looking at the
link you give it seems that Python bindings already exist, so one approach
would be to port those.
Finally, make sure you have some specific goals in mind as to what you want
to be able to do from the Ruby side.