hi
yes it is possible to do what you require.
for bets below the betfair minimum(you do this at your own risk),you have to tick the Allow small bets in the betting options, in the settings at the top right of the bot screen.
i have completed a basic trigger for you to try.
in the constants you can set
bet amount
minimum lay price
maximum lay price
maximum number of bets per market
there is no time condition as you never mentioned any time requirement, if you need this or any other condition adding you only have to ask.
the trigger will lay any selection at your set minimum price, that has a lay price between your set prices and if there are no more than (your set number) of matched and unmatched lay bets in the market.
please use test mode until you are happy with your settings
mcbee
download the trigger below