Consigure the system by editing config.sh
You can change BM addresses, deal filling timeout (DEALS_DEPOSIT_TIMEOUT),
electrum command to use (ELECTRUM, by default it uses testnet), PGP keys
to use (DEALS_PGP_TO_ACK_DEAL to sign deals, DEALS_JUDGE_PGP to check
arbitration commands). You can change location of all files created bu the
system: DEALS_BASE.

Add the following to ~/.config/PyBitmessage/keys.dat :

apienabled = true
apiport = 8442
apiinterface = 127.0.0.1
apiusername = username
apipassword = password

Run BitMessage.

Setup electrum:

. config.sh
$ELECTRUM setconfig rpcport 7777
$ELECTRUM setconfig rpcuser "username"
$ELECTRUM setconfig rpcpassword "password"
$ELECTRUM create

To start and stop Electrum use start_electrum.sh and stop_electrum.sh

Then you run the following scripts in loop:

read_registrations.sh (it reads new registration messages from BM)
accept_deal.sh (reads new deal creation messages from BM)
update_deals.sh (checks state of deal filling with money)
judge.sh (receives arbitration messages)