You're on the right track. You had the right idea loading the IOS image via xmodem. The only easier option is to use a PCMCIA/CF card reader. However, before doing the code load, we need to change the configuration register to bypass the startup configuration when IOS loads. Assuming you keep the default console settings, the configuration register would then be 0x2142.
IOS will then load, and you should be able to enter enable mode to set the config register back to 0x2102, and configure the device. I'd recommend reformatting your flash file system and redownloading the IOS image to flash once in IOS.