Other source game's models in GMod without extracting from GCF?

[Risonhighmer]

Is this possible? Say, for example I wanted to have the models from Left 4 Dead 2, Dark Messiah, and SiN Episodes in GMod. Is there a way I can get GMod to look in those GCFs for models, much like it does for Halfe Life 2, Counter Strike, and Team Fortress 2?