The method of choice would be p-ethoxy-phenylhydrazine + dimethylaminobutyraldehyde acetal condensation. For this reaction you can find some (important) postings at the Hive.
For the higher alkyloxy DMT analogs there are no 5-HT2A binding data. I heard that 5-nonyloxy-DMT at a low (undetermined) dosis resulted in a two-day very strong (but not unpleasant) tiredness, possibly an indicator of 5-HT2(C?) antagonism.
I found the following literature in my references database:
Methylthio-DMT receptor data:
J. Med. Chem. 25, 1381 (1982) T. B. Kline et al. (Lil. Ref. # 261)
4-, 5-, 6-(di)MeO- and MeS-DMT, rat stomach fundus strip data, photoelectron spectra
5-Alkoxy-tryptamines:
J. Med. Chem. 37, 2828 (1994) R. A. Glennon et al. (Lil. Ref. #384)
NonO-tryptamine, serotonin, and sumatriptan, 5-HT1A, 1B, 1Dalpha, 1Dbeta, 2A, 2C, and 3 receptor binding data, AC activity data
J. Med. Chem. 39, 314 (1996) R. A. Glennon et al. (Lil. Ref. #385)
AlkylO-tryptamine 37 subst. 5-alkyl-O- and 5-alkanoyl-O-tryptamines and cyclic analogs, human 5-HT1A, 1Dalpha, and 1Dbeta receptor binding data, NonO-DMT from tryptamine with NaCNBH4, formaline, and acetic acid, yield 25%
J. Chem. Soc. -, 1573 (1955) Ph. Buu-Hoï et al. (Lil. Ref. #386)
p-AlkylO-anilines p-alkylO-anilines from p-OH-formanilide via p-alkoxyformanilide with alkyl bromide, and alkaline hydrolysis
J. Med. Chem. 27, 347 (1984) C. D. Selassie et al. (Lil. Ref. #387)
p-AlkylO-anilines p-alkylO-anilines from p-OH-acetanilide via p-alkoxyacetanilide with alkyl bromide, and alkaline hydrolysis
J. Med. Chem. 15, 307 (1972) E. M. Kosower et al. (Lil. Ref. #388)
p-Pentyl-O-phenylhydrazine p-pentyl-O-phenylhydrazine from p-pentyl-O-aniline with 1. NaNO2 / HCl 2. SnCl2 / HCl
Coll. Czech. Chem. Commun. 38, 595 (1972) M. Machková et al. (Lil. Ref. #389)
p-AlkylO-anilines p-alkylO-anilines from p-OH-trifluoroacetanilide via p-alkoxy-trifluoroacetanilide with alkyl bromide, and gentle alkaline hydrolysis