Is it possible to include a sell rule in the backscanner that would execute if the stock has not made at least 10% gain at the end of 10 days  ?   In other words, a "lack of progress" sell rule..   thx

Assumming the enterCondition logic is not overly complicated you can produce an exit rule with something like this:

static InTrade as boolean
static TradeDays as integer
static EnterPrice as single

if isfirstbar then
  inTrade = false
  tradeDays = -1
end if

if inTrade = False then
   if  enterCondition = True then
       inTrade = True
       tradeDays = 0
      '
      ' assume enter next day open
      '
      enterPrice = price.open(-1)
    end if
else
  tradeDays += 1
   if tradeDays >= 10 andalso _
   price.close < EnterPrice * 1.10 then
      '
      ' time to exit based on lack of progress
      '
      pass
      inTrade = False
      tradeDays = -1
   end if
  '
  ' the very trick part is that you need to mimic the alternate exits as well 
  ' to ensue that the correct entries are taken
  '
  if otherExitConditions then
    inTrade = false
   TradeDays = -1
  end if
end if

The backscan would just look for pass to exit. You need to provide the logic for the enterCondition.  The same logic used to triger the Entry, assuming buy next day open.