<p>I'm working on an embedded linux system in C, I'm looking for the source code to the equivalet of SendARP in Windows. Any pointers?</p>

This may be of interest:
http://cvs.linux-ha.org/viewcvs/viewcvs.cgi/linux-ha/resources/heartbeat/SendArp.in?rev=1.4
It is an implmenetation in a Bourne Shell script.