Luis,
The AEP firmware is proprietary, so you will not be able to build a custom image of that firmware. However, you can use the mLinux distro based off of Yocto found here: http://git.multitech.net/cgi-bin/cgit.cgi/mlinux.git/
Using mLinux you can add the flask and sqlalchemy pip packages to that, build the packages, and use the .ipk files (packages) that generates to install on your AEP.
You should use the version of mLinux that the AEP firmware you have installed is based off of. To figure that out via an ssh connection to the Conduit: “cat /etc/issue” will tell you what the mLinux version is.