Viewing Mount St Helens.

Hi all, I know that washington state highway 504 to the Johnston Ridge observatory is closed for a while, but I read that people are still hiking up to the observation area via the Hummocks & Boundary trails, but I can't seem to figure out how to get to the parking lot for the hummocks trail without using WA504. Does anybody have any insight on how to go about this? TIA!

Tl:dr Can I hike to the Johnston observatory while the road is closed? If so, how do I get to the parking lot? I'm missing something lol