I modified it so that you can either:

• choose any month (and any week in it)
• choose any week of the year based solely on its year week ID
• choose any whole month

DEFPARAM CumulateOrders = false
////////////////////////////////////////////////////////////////////////////////
//                              Week Count
//
//returned data:
//
// - Wcount  Week num of the month
// - LastMM  Month to which the week belongs (can be different from that on chart)
// - Wyear   Week num of the year
//
ONCE Wcount = 0
ONCE Wyear  = 0
ONCE LastMM = 06
mm          = OpenMonth
wd          = OpenDayOfWeek
yy          = OpenYear
dd          = OpenDay
DayMax      = 31           //each month has 31 days by default
//                          (below, exceptions will be dealt with)
// check for any month with less than 31 days
IF mm = 4 OR mm = 6 OR mm = 9 OR mm = 11 THEN  //Apr, Jun, Sep and Nov have 30 days
DayMax   = 30
ELSIF mm = 2 THEN                              //Feb has 28 days (29 on Leap Years, which occur on almost all 4-year boundaries)
// check whether it's a Leap Year for February
DayMax = 28                    //let's default to 28
IF yy MOD 4 = 0 THEN
IF yy MOD 100 = 0 THEN      //NOT a Leap if it, as it can be divided by 100, but not by 400
IF yy MOD 400 = 0 THEN
DayMax = 29           //it's a Leap Year, since it can be divded by both 100 and 400
ENDIF
ELSE
DayMax    = 29           //can be divided by 4 and is not a century start, so it's a Leap Year
ENDIF
ENDIF
ENDIF
// check & count every Monday (or later, if Monday is not a trading day)
IF (wd >= 1) AND (wd <> wd[1]) AND ((wd < wd[1]) OR (wd[1] = 0)) THEN
Wyear  = Wyear + 1
Diff   = (DayMax - dd) + 1
LastMM = mm
IF LastMM <> LastMM[1] THEN
Wcount = 1                     //restart from 1 each new month when Monday os the 1st day
ELSE
IF Diff >= 4 THEN              //if not a full week, then it belongs to the prior month if at least 4
Wcount = Wcount + 1         //  days belong to the prior month
ELSE
Wcount = 1                  //  otherwise it's the 1st week of the new month
LastMM = LastMM + 1
IF LastMM > 12 THEN
LastMM = LastMM - 12     //when computing the new month, make sure it's not greater than 12, if
ENDIF                       //  it is, then it's January
ENDIF
ENDIF
ENDIF
// restart year count on Jan. 1st
IF (LastMM = 1) AND (LastMM <> LastMM[1]) THEN
Wyear = 1
ENDIF
////////////////////////////////////////////////////////////////////////////////
TradeON = 1
// disable trading in weeks 1 and 3 of October
IF (LastMM = 10) AND (Wcount = 1 OR Wcount = 3) THEN
TradeON = 0
ENDIF
IF close CROSSES OVER average[20,0](close) AND Not LongOnMarket AND TradeON THEN
BUY 1 CONTRACT AT MARKET
ELSIF close CROSSES UNDER average[20,0](close) AND Not ShortOnMarket AND TradeON THEN
SELLSHORT 1 CONTRACT AT MARKET
ENDIF

you change line 62 to use more months:

IF ((LastMM = 10) AND (Wcount = 1 OR Wcount = 3)) OR (LastMM = 1 AND Wcount < 3) THEN
   TradeON = 0
ENDIF

or use it for yearly week ID (1 to max 53):

IF Wyear < 3 OR Wyear > 50 THEN
   TradeON = 0
ENDIF

or use any other combination of the three values:

IF (LastMM = 10 AND Wcount = 1) OR (Wyear > 51) OR (LastMM = 8) THEN
   TradeON = 0
ENDIF