One of the biggest “errors” one gets when trying to view ArcIMS services in AGX is the dreaded “Unknown spatial reference” when adding them. This occurs because the projection has not been set for the service and logically AGX cannot display them. The 9.2 ArcDoc should explain how to set the projection withe the AXL files, but way back in Feb 2006, Jeremy Bartley wrote a blog post about how many ArcIMS sites had their projection set inside the huge MapDex site.
One of the most disturbing things I have found out from building Mapdex is the lack of proper projection information set for mapservices. It turns out that about 56.5% of mapservices lack a projection or cannot be assumed to be geographic. Only 31.3% of mapservices have a valid projection while 12.2% can be assumed geographic.
Better get cracking all you ArcIMS administrators and update those AXL files. As Jeremy noted back then, there is a great ArcUser article about Georeferencing ArcIMS Services.