David,
Here is the command syntax as it is displayed at the switch's CLI.
HP ProCurve Switch 2650(config)# ip icmp burst-normal help
Usage: ip icmp burst-normal <0-1000000>
Description: The maximum number of icmp replies to send per second.
HP ProCurve Switch 2650(config)#
To set a maximum of 5000 ICMP replies per second, the command would be:
ip icmp burst-normal 5000