This should do the trick:
arima('ARLags',1,'MALags',[1 8])
ans =
ARIMA(1,0,8) Model:
--------------------
Distribution: Name = 'Gaussian'
P: 1
D: 0
Q: 8
Constant: NaN
AR: {NaN} at Lags [1]
SAR: {}
MA: {NaN NaN} at Lags [1 8] <--------
SMA: {}
Variance: NaN