during my migration I tried the same like you and neither succeded.
My step by step migration finally looked like this:
1.) say goodby to full functionality of your beloved program for some weeks.
2.) create a main.c file with a dummy function (hello world) and make it work.
3.) take a simple one of your wdl.files (e.g. a menu.wdl) and transform it to a menu.h and menu.c file. Include these files in your include list of main.c and bring it to the point where it runs.
4.) repeat 3.) for all other wdl-files. Step by step you regain you full functionality.
Like JCL says, you will end up with a Lite-C program and empty wdl-files.
Of course, this is the long and stony way. It took me some weeks to finish migration of a 30 000 line program. But believe me, you will learn C-Lite very fast and you understand how it works.
And, last but not least, you will notice a lot of chances to improve and clean your old code. It's all these 'I will do it later, when I have time'. But you never found the time to do it. NOW is the chance to do it.