I think that poide use only include/lib from project-file.
You can insert INCLUDE and LIB environment variables to project.file from Project -> project options ... tab Folders button Defaults
EDIT:
Maybe poide.exe and pomake.exe create INCLUDE and LIB environment variables when you run them.
PellesCDir is used too.
INCLUDE = $(PellesCDir)\Include;$(PellesCDir)\Include\Win#
LIB = $(PellesCDir)\Lib\Win#
Test program fake.c for CC and LINK:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
printf("\n");
for (int i = 0; i < argc; i++)
printf("%s ", argv[i]);
printf("\nINCLUDE=%s\n", getenv("INCLUDE"));
printf("LIB=%s\n", getenv("LIB"));
printf("PellesCDir=%s\n", getenv("PellesCDir"));
return 0;
}