I think your best bet would probably be to pathwalk to Asgard via a physical space that resonates with it. Otherwise, you could just project straight to it if you're proficient in projection or get the aid of one of the Aesir or Asynjur.
Also note that the Aesir/Asynjur are not the only Gods in Norse Paganism. There's also the Vanir and (some would consider) the Jotnar. Personally, I view all of the Vaettir as having the capability of being a God as the ones I work with are ones I have deep reverence and respect for (I personally include the Dokkalfar in Rokkatru and the Dvergar can be held as Gods of craftmanship in their own right).
If you're wanting to travel to Asgard via Bifrost, then I would not recommend calling upon the aid of Thor as he is cited in the lore as being too heavy to cross it (so he has to wade through the river below it). Honestly, Sleipnir and Odin would be good bets on aiding your travels there.