I've been trying to add the BT Wifi app on my daughters Nook HD via the Play store but apparently the device isn't compatible with BT Wifi. Don't really understand why that would be as the Nook runs ICS in the back end albeit with their own front end. It can't be an Android version issue as I've run the app on Gingerbread and Froyo before so is it just a case of the device not being 'listed' as compatible in Google Play?
Have you tried side loading?
If not, you could always grab another android device, install the BTWifi app on this this (if you've not already).
Then install an 'apk extractor' from the play store and if the device doesn't have a 'file manager', install one of these too.
Open the extractor and look for the BTWifi app and extract it - note where the apk file gets placed. Open the file manager and look for this file, open it and you should see the BTWifi apk file.
Connect this device to a laptop/PC and copy the apk file to the desktop (or your normal location).
Disconnect the device.
Grab the nook and make sure you have ticked the option to allow installs from unknown sources. Install a 'file manager' on this device (again if this doesn't come pre installed). Connect to the laptop/PC and drag the apk file to the nook (in to the android file -> data location). Disconnect the nook, open the file manager, find the apk file, click on it and install BTWifi from there.
Above sounds like it's going to be a pita, but it isn't. Also note above written from memory, so if you hit a wall, give us a shout;), but not sure what "front end" these use.....?
I tried sideloading, but on a Nook HD it's a messy old business http://bookclubs.barnesandnoble.com/t5/NOOK-HD-HD-Support/Side-loading-apps-how-is-it-done/m-p/14635...
I see what you mean:(
My only other suggestion is to try tethering (which kind of defeats the object).
Raise it in the ideas bank section of these forums, something along the lines of 'BTWifi on a Nook' and see if the mods pass it on.
(though getting the BTWifi guys to implement a version for the BBerry took some time:()