Im sure the default settings will be pretty much what you will need. I think you can reach the setting at the top of the strut and may be able to reach under the car to set the lower setting but could become a problem once some road grime makes its way there. Could be a good idea to cover the lower one with some tape or a plug of some type to eliminate the grime getting in there.
You could go and see Ric Shaw or another suspension tuner with MR2 knowledge(there is a very good one in Sutherland Shire) in the new year so he can set the ride height correctly. It will certainly save a lot of grief trying to get it right on your own.
So how has the running in coming along? Has the engine loosened up?
How is the power delivery?