Sounds like you know what you are doing. I have openpogo installed on a USB drive. Here is the transcript for installing screen & python.

-bash-3.2# ipkg update
Downloading http://openpogo.com/repo/Packages
Updated list of available packages in /opt/lib/ipkg/lists/cross
Successfully terminated.
-bash-3.2# ipkg install screen
Installing screen (4.0.3-2) to root...
Downloading http://openpogo.com/repo/screen_4.0.3-2_arm.ipk
Installing termcap (1.3.1-2) to root...
Downloading http://openpogo.com/repo/termcap_1.3.1-2_arm.ipk
Configuring screen
Configuring termcap
Successfully terminated.
-bash-3.2# ipkg install python26
Installing python26 (2.6.2-2) to root...
Downloading http://openpogo.com/repo/python26_2.6.2-2_arm.ipk
Installing readline (6.0-1) to root...
Downloading http://openpogo.com/repo/readline_6.0-1_arm.ipk
Installing bzip2 (1.0.5-1) to root...
Downloading http://openpogo.com/repo/bzip2_1.0.5-1_arm.ipk
Installing openssl (0.9.8k-1) to root...
Downloading http://openpogo.com/repo/openssl_0.9.8k-1_arm.ipk
Installing libdb (4.2.52-3) to root...
Downloading http://openpogo.com/repo/libdb_4.2.52-3_arm.ipk
Installing zlib (1.2.3-3) to root...
Downloading http://openpogo.com/repo/zlib_1.2.3-3_arm.ipk
Installing sqlite (3.6.14.2-1) to root...
Downloading http://openpogo.com/repo/sqlite_3.6.14.2-1_arm.ipk
Installing ncurses (5.7-1) to root...
Downloading http://openpogo.com/repo/ncurses_5.7-1_arm.ipk
Installing libstdc++ (6.0.9-6) to root...
Downloading http://openpogo.com/repo/libstdc++_6.0.9-6_arm.ipk
Installing ncursesw (5.7-1) to root...
Downloading http://openpogo.com/repo/ncursesw_5.7-1_arm.ipk
Configuring bzip2
update-alternatives: Linking //opt/bin/bzip2 to /opt/bin/bzip2-bzip2
Configuring libdb
Configuring libstdc++
Configuring ncurses
update-alternatives: Linking //opt/bin/clear to /opt/bin/ncurses-clear
Configuring ncursesw
Configuring openssl
Configuring python26
Configuring readline
Configuring sqlite
Configuring zlib
Successfully terminated.
-bash-3.2#