Want to know if this trigger is doable

Hello,
Guys i want to ask you something.

Can i do something like this with trigger function?

I select a horse and tell him to auto bet a lay immediately when market goes in-play, asking an odd based on his BSP.

Example:

I check a horse X and tell him to auto place a lay bet when market goes in play, asking the price (BetfairStartingPrice *90%).
If BSP were 10 i want to ask price 9 in-play very fast.

Guys thanks for reading, i hope i made myself clear.
Any help will be appreciated.

Thanks!