Variable microsecond delay in C

Hi there

I'm currently busy with a project that generates PPM frames to control an RC plane. I'm using mikroC to compile
my project and I'm using a PIC16F627A.

I need a way to generate precise microsecond delays at 4Mhz clock. It should also be adjustable (when I
call the procedure it must accept the custom delay time as an argument of the procedure).

My idea is the same as the built-in delay API's, but it must accept variables and not constants (so that I can
adjust delay times in runtime).

How can I generate the microseconds delay routine in C?

Thanks in advance
JeanTech