Catalyzes the transfer of diphosphate from ATP to 6-hydroxymethyl-7,8-dihydropterin (6-HMD), leading to 6-hydroxymethyl-7,8-dihydropterin diphosphate (6-HMDP). 6-hydroxymethyl-7,8-dihydropterin + ATP = (7,8-dihydropterin-6-yl)methyl diphosphate + AMP + H(+) Cofactor biosynthesis; 5,6,7,8-tetrahydromethanopterin biosynthesis. Belongs to the archaeal 6-HMPDK family.