What I have discovered is that if you simply double-click on the Windows firmware installer (in this case, IDPFLIDR1004V0050.EXE), it will extract all of the files into a folder below your Windows "temp" directory. You can then click the Close button in the Windows flash program and the temp files will not get deleted. The folder name will be some randomly system-generated thing like PAC36.tmp.DIR and inside that folder you will find the V0050.HEX file.
Copy the V0050.HEX file and MTKFLASH.EXE to a DOS boot floppy and reboot. I got version 1.80 of MTKFLash from the ZIP file that contained the 047t beta firmware. I used the following command and everything seemed to work fine:
MTKFLASH 3 w /c V0050.HEX
I took out the normal /m16 parameter from the command because we're using one big HEX file instead of the usual 16 small files.
If your BTC drive is not connected to your Secondary Master IDE channel, then change the "3" to the appropriate number.
Hope this little tip is helpful for anyone out there who has been frustrated that BTC never posts the DOS firmware on their website.