router command to change bandwidth limit for a MAC address

I use DD-WRT to limit WAN bandwidth to one MAC address using DD-WRT's web interface. The key entry in the web interface (in "NAT/QoS" tab's "QOS" tab) is "MAC priority", which I normally set to 10000 "WAN Max Down kBits". I temporarily sometimes increase this value to 60000, but this is never needed permanently, so it seems wasteful to set this in the web interface (since it overwrites the NVRAM flash memory which has limited write cycles before wear-out). So, is there a way to temporarily increase this value with some command I could issue during a telnet session (and does not overwrite the NVRAM)? I have tried some wild guesses with the tc command, but been unsuccessful.