I found it rather unfortunate that these wonderful models weren't included in the SFM Workshop and I've struggled to convert the models into ones that can be used in SFM.
This is why I've started this discussion in the hopes that someone with more understanding of the program and its intricacies could tell me:

How to add the Skullcrawler to SFM

I should also note that the error I have repeatedly faced states...
sfm model version 402653184 should be 7