Assuming you want anhydrous methanolic ammonia you can do the following. Heat up your solution of aqueous ammonium hydroxide, that will drive off ammonia gas (but it will have water vapour with it). Pass the gas through a drying agent like potassium hydroxide pellets, and bubble the dry ammonia into anhydrous methanol. Ammonia is very soluble in methanol so be wary of suck-back. Appropriate use of Dreschel bottles should do the trick (see pic). Attach a drying tube on the end if you want to exclude moisture.