That's what I would use on "normal" Windows, however CE seems to have different syntax for ARP command, it asks for filterfiles, regfiles, outputfiles, etc.
Check it out:
Pocket CMD v 5.0
\> arp -s 123.15.36.25 00:00:15:ce:df:01
Bad option -s.
Usage: arp -i|-d [-f<FILTERPATH>] -i<REGFILE> outputfile
Options:
-u Filter Up
-d FIlter Down
-f<FILTERPATH> Directory location of filter files
-i<REGFILE> Input Registry file (SRTF)
Error code (1)
\>
</REGFILE></FILTERPATH></REGFILE></FILTERPATH>