Oh man. I'm also interested in what you wanted to use this for :)
I think the way to go would be to use the Espruino as a SPI interface to it's configuration memory. Have a look at the fpga-shield and the build log :)
There are things like SystemC and other CtoHDL projects that I've found utter crap after trying anything but the samples they provide. They're fun and all, but even for an amateur like me, you quickly get to a blocking point.
Did the project you worked on @Gordon compile C into opcodes for a soft core, or did you try to make a C to HDL thingy?
I like how pshdl.org approaches things. I've not tried it yet.
In the end, FPGAs are configured; not programmed.