Thank you very much sir.
So, I should use the following script:
;eff = mnl_model(mnl,d)
;eff = mxl_model(rppanel,d)
;rdraws = gauss(3)
;rep = 500
;model(mnl_model):
U(alt1) = b1[0.1] * x1[1,2,3] + ... --> Beta estimates from MNL
;model(mxl_model):
U(alt1) = b1[n,0. 15,0.05] * x1[1,2,3 ...