Generate a new key:
gpg --expert --full-generate-key
New subkey (and for a lot of other things):
gpg --expert --edit-key <key>
To see the IDs and fingerprints of the subkeys:
gpg --with-subkey-fingerprint --keyid-format long --list(-secret)-keys
Export keys:
gpg --armor --export
gpg --armor --export-secret-keys
gpg --armor --export-secret-subkeys
In order to export only one subkey, add ! to the end of key fingerprint:
gpg --armor --export-secret-subkeys 141E64008A4BF92AFC62100A31EF9F657DDE6053!
See content of an export:
gpg --list-packets export.asc
cat export.asc | gpg --list-packets