upgrade tinyrom on a router 801

Hi, I'd like to update the rommon on a router cisco 801. so i copy the new rommon image (by tftp) in the flash:

Directory of flash:/

0 ---- 49096 Aug 3 1999 01:22:22 +02:00 TinyROM-1.2(2) 1 -r-x 2759760 Dec 6 1999 23:05:27 +01:00 c800-y6-mw.120-7.T 44 -r-- 49096 TinyROM-1.4(1) 45 -r-x 4864264 Feb 12 2004 00:27:20 +01:00 c800-y6-mw.123-6.bin

8388608 bytes total (524288 bytes free)

but when the router starts, i stay with TinyRom1.2(2). How can i select the new TinyRom? I try to read the help but i don't realy understand how to do it.

Thanks for your help Vincent