Bitgen 0.18 has been released:

http://bitgen.org/

This release includes support for electrum seed generation.

Here is an example:
http://bitgen.org/electrum_btc_example_private.pdf

To generate an electrum seed, use the command "electrum" followed by the generation method, for example:

$ bitgen electrum random

This will generate a 24 word seed using random data from "/dev/random"

Other possible generation methods are "hash", "mnemonic", "hex", "dice" and "brain".

For example, the following command will generate a 24 word seed from 100 dice values:

$ bitgen electrum dice 6123623123652635162356516316213666166253162356253654545162456125213612536523615 236512631532131236616

The default seed size is 24 words, but this can be changed by adding "words" followed by the desired number.
The following command will generate a 18 word seed:

$ bitgen electrum random words 18

Possible values are 12, 15, 18, 21 and 24.

An optional "account name" can be specified by using "name", for example:

$ bitgen electrum random name "My test"