Thank you so much dubdisciple! That is an amazingly detailed description! I will do that as soon as I can when I get back home tomorrow evening. I have managed to get the loops working in a similar fashion in RXP, and I had even used the musical note to insert the midi pattern into the track view. With Dimension though it was more just an issue of actually knowing how to load the REX files into it. So really your description is amazingly helpful as it actually says where to click and what to do.
Also I really wanted to be able to try with Dimension instead because of that weird RXP problem that I mentioned before. Hopefully Dimension won't do the same thing as well. I do have one general question though, even though it's probably not necessary now that you have told me how to use the REX files in both RXP and Dimension...
If I do what you said and simply drag the loops directly into the timeline without being in an instrument track, then surely they will just be in a plain midi track with a sequence of notes like c1 c2 c3 etc. But if they aren't outputting into a VST instrument then how will they make any sound. Surely the output would just be silence? I know that this is going well beyond the scope now of my original question, and I'm sure that what you told me about how to load them into dimension will be more than enough for what I need, but it is interesting to know anyway.