Any progress? Have you looked at the link stat files in the Links folder?I believe that's where you connect items with the proper root template and define object categories, player level needed for them to appear, etc.
object itemstat "SKILLBOOK_ExplodeSelf","71ca015c-df88-43b2-893b-2aaace71b0ed","",0,0,"SkillbookFire",1,1,2,0,8,20
But I'm a bit confused about the ID: 71ca015c-df88-43b2-893b-2aaace71b0ed
It appears that these ARE reused to a certain degree in the links file for nearly identical items. For example, a breastplate might have 8 versions that all have the same ID, but there will only be one reference in the armor.lsx to that ID. Somehow these are used for level-mapping certain stats and requirements, but I'm not entirely sure how. That doesn't really matter for skillbooks, since there's only one version per each skillbook. But maybe you just need to copy the teleport skillbook info in the LSX, make the proper stat references, create a new ID with a generator, and then create a link in the links file.