Fitted an alternator to my ST200 a few years back, one of the most awkward jobs I have ever done, access was very difficult, the only thing I think may have made the job easier would have been to use a 2 or 4 post ramp, lying under the car with only the space provided by axle stands did not help, on the plus side it is doable, theres not many bolts and my car seemed a touch quicker after I changed the alternator but no idea why!!
Kenny