Guys, I just replaced the steel coolant pipes behind the engine on my 97 sts yesterday. It's not that bad of a job. I did the water pump at the same time and I spent 8 hours total on the job(s).
I just removed the front engine cradle bolts and lowered the engine down about 6 inches. Of course you have to take off the electric fans, etc. I was able to reach everything from above by doing this. Yeah, I had to lay on the engine to reach most of it, but it wasn't that terrible.
I tried to find advice on this forum on it with no help, so I thought I'd post for someoene else to find.
If they need replacing, don't do like someone else on here did with the hoses. Fix it right. It's not near as bad as it looks.