how to optimize non-extern stoploss in ex4 expet advisor ?

 

I found a free ex4 expert that is shared on the web many years ago

it looks promising

it uses a fixed big stoploss (over 100 pips)  

I would like to optimize this stoploss

but the problem is that it is not an extern variable  so it doesn't appear in the expert inputs when attaching the expert to a chart

 how can this stop loss be optimized or at least another stoploss be backtested by the tester?

can another expert advisor be built to take entry and exit  in profit signals from the ex4 expert with different stop loss used ? 

any third party software can help ? 

any solution ?