what I did was basically following the instruction in this post:
but getting fastboot to work in Mac is not easy. What I end up doing was to download the fast boot binary from HTC website (google it) and then specify the vendor and product id manually in the command line. you can find out product and vendor id of your usb drive in profiler in mac book.
the command is something like this ( you should put the IDs of your device, they could be different)
./fastboot -p 0x0700 -i 0x0955 boot ~/Downloads/recovery-cwm_188.8.131.52-sam-tab-10.1.img
but here it is, I have 3.1.