[racket] Programmatically start a big-bang?

I'd like to write a library function that takes a hash table of
handlers and starts a running world in big-bang style, for example:

(my-big-bang
 0
 (make-immutable-hash
  `((on-tick . ,add1)
    (stop-when . ,(lambda (x) (> x 100))))))

Is there an interface that I could use to write this?  I suppose I
could try to generate a syntax object containing an appropriate
big-bang and eval it, but that seems like a big hammer to wield here.
I've poked around a little bit in 2htdp/ but haven't found anything
provided that seems to fit the bill.

Motivation: I want to support big-bang in a language that doesn't
support macros (yet), and I don't want to add special-case syntax for
big-bang.  I'd like the usage in that language (Pyret, which has
Python-like syntax) to look like:

big-bang(init, {
  event_name: event_handler,
  ...
})

Which calls something like `my-big-bang` under the hood.

Thanks!
Joe