exactly. as of now, there is no android rom for the internal flash (nand) to replace the current windows mobile os. but there are still ways to get android working alongside winmo, by simply putting it on the sd card.
basically, what you need is a rom, haret and ts-calibration+startup.txt.
for the rom itself, there are dozens of different roms around this very forum section. look for the most recent ones and compare them by the features needed. some of them hardly have any support for the blackstone hardware, when it comes to camera, sound, BT, 3.5mm jack, calling... and are purely for fun and apps, some others are more suitable for everyday use. make sure to read a few posts of user feedback to get what you want.
most roms come with their own haret package (the winmo program to boot android), which, like the rom itself, needs to be extracted to the sd card root.
ts-calibration is the file needed to store the touch screen calibration, so you don't have to align it yourself, which can be tricky in android.
startup.txt stores the boot commands, which can be altered to your needs, have a look at a few of them and pick the best one (which seems difficult at first, but you can search any command in there to find out what it means). some come with overclocking or different values which can speed up or slow down the device, it set wrong.
and, to sum it all up, here is a tutorial thread describing the whole installation (well, copy) process:
it is not completely up to date, but you can use the same tutorial, the same haret, ts-calibration and startup for other, newer roms, like blazn 2.2.2 or whatever you want.