fcron would be needed to be patched to use DSME/iphb socket for the heartbeat. Very easy modification.

--- edit ---

Yes, really all that's needed should be something like

....
sockfd = iphb_get_fd(g_iphbdHandler);
int delta = seconds_to_wait / 4;
r = iphb_wait(g_iphbdHandler, seconds_to_wait - delta, seconds_to_wait + delta, 0);
....

or something similar to the main_loop(), and of course some bits of initialization.