You can find the key at the location MainMemory spoke of with a hex editor. Although some levels crash SALVL for some reason. You can load individual models that are part of the crashing level's geometry by locating the object structs that make up the level by using IDA Pro and MainMemory's IDC script (that's on retro's repository) and load those objects with SAMDL. All of Mystic Ruin's LandTables crash SALVL, but you can load the models separately with SAMDL if you know the right address and key of each object. It's not very cool though since you can only load one model at a time and there are hundreds of them that make up the level sometimes. Unfortunately, some objects even crash SAMDL - which might be the cause for why they're also crashing in SALVL.