Oh, that yield sucked bigtime. Thanks anyway. As it turns out, I was lucky and found a much better yielding method in JOC 25, 1453 (1960):
4-Methyl-2,5-dimethoxybenzyl chloride
Gaseous hydrogen chloride was bubbled into a well-stirred mixture of 200 ml. of 35% formaldehyde, 100 ml. of conc. hydrochloric acid, and 400 ml. of dioxane for 15 min. at such a rate that the temperature of the mixture remained between 55-60°C with no external heating. To this mixture 152g (1.0 mole) of 2,5-dimethoxytoluene was added, dropwise, over a period of 20 min., while the temperature was maintained between 55-60°C. When the addition was completed, the passage of hydrogen chloride was stopped. The mixture was cooled and poured into 2 1. of ice water and 300 ml. of ethyl ether. The aqueous layer was extracted twice more, with 250-ml. portions of ether. The combined ether extracts were washed with cold water until the washings were neutral to litmus, then dried with anhydrous magnesium sulfate, and evaporated under reduced pressure. The residue was distilled through a 4-in. Vigreux column to give 110-130g (55-65%) of colorless liquid, b.p. 144-153°C/14-16mmHg, which solidified on cooling. Recrystallization from acetonitrile gave white crystals, mp 61.5-62.5%.