Federated wiki is just one more document format that hopes to play well with others and bring something new to the party.
Consider the strengths and weaknesses of federated wiki before choosing an import strategy.
Strengths: Federated wiki format is simple, extensible, and open. It embodies the Creative Commons notions of attribution and share alike. It travels well over networks using familiar web protocols. It can be interactive and mobile friendly.
Weaknesses: Federated wiki format has limited built-in formatting. It rejects the conventions of the printed page. It is new and unproven, especially in foreign language capabilities.
Consider the long term purpose of both the original document and the imported version. The wiki version can be either the reference document or a way to find and use the original which remains the ultimate reference.
Wiki as Reference: If wiki's natural collaboration is important for acquiring and refining original material, then keeping and evolving this material in a living document on the wiki makes sense.
Wiki as Index If wiki's natural collaboration will be valued mostly to comprehend and deploy a complex work already published by more traditional means then wiki is best employed as a an index to, summary of, or comments on the work preserved elsewhere.
Consider the methods available for importing content into the federation. A few formats can be dragged and dropped into wiki from the desktop. Other formats can be read by a batch script that emits one or more federated wiki pages all at once.
Drag and Drop: This is most likely to be useful for importing a passage, an image, or a table of data. See How to Add Paragraphs. Start by using the export features of your desktop authoring tools to write a compatible text file. Then drag that to a wiki to make individual paragraphs, images or datasets.
Batch Import Script: This requires programming. You are unlikely to find a complete batch converter already written because they typically include many organizational decisions aligned with the needs of a specific work.
Don't try to merge distinct works into a single wiki site. Let each work have its own site. Once in the federation, the site's content can be remixed into many other sites including application specific anthologies.
Excerpts from Eric Evans' Domain Driven Design software pattern book were imported using a batch script 
to produce a whole site dedicated to this single work.