Given the intent to have relatively straightforward C code and a tiny runtime, you pretty much have to ditch them or you're not going to get anywhere at all.
Plus honestly most of the uses of continuations that would make sense in the sort of relatively low level code this is aimed at can be built out of a few special purpose macros (and possibly a small amount of crying) - scheme code tends to lean on first class continuations for a lot of things that don't really need them, Because It Can.
e.g. Paul Graham's On Lisp shows how to build (a subset of) continuations out of macros, and getting something like clojure's 'recur' out of that would probably give you simpler macros than pg's code uses.
Plus honestly most of the uses of continuations that would make sense in the sort of relatively low level code this is aimed at can be built out of a few special purpose macros (and possibly a small amount of crying) - scheme code tends to lean on first class continuations for a lot of things that don't really need them, Because It Can.
e.g. Paul Graham's On Lisp shows how to build (a subset of) continuations out of macros, and getting something like clojure's 'recur' out of that would probably give you simpler macros than pg's code uses.