Well, I answered my own question, it was pretty obvious.
But, if anyone else has the same issue, use the BuyPrice, SellPrice, ShortPrice and CoverPrice commands to set the entry price to wherever the stop-limit order should be if trade conditions are met, and also might need to use-
Example to have a stop-limit buy order at the previous candle's high price (backtest settings to trade NEXT BAR ON OPEN):
buycondition = H>Ref(H,-1);
Buy = Cover = buycondition;
SetOption("PriceBoundChecking",False); //disables checking and adjusting buyprice/sellprice/coverprice/shortprice arrays to current symbol High-Low range.
BuyPrice = CoverPrice = IIf(buycondition,Ref(H,-2),O); //must set buy price to high 2 ticks ago since I am trading on next-bar open