I have read about the CWE for MHRB to be the most effective way to brew it.

The trick was apparently to powder it, put it in room temperature water and shake it vigorously every few hours for 3-4 days, after that just filter it out good and it should be as potent as when eaten straight.

I was wondering if I could do the same with powdered rue seeds.

This method might not be the fastest but seems fairy easy to do to get the most bang for the buck. The question is, does it work?

I don't own any capsules or even a scale for that matter but I would prefer to drink it in a liquid form rather than swallowing the whole seeds one way or the other.

You could make the water slightly acidic with citric acid like lemonjuice, pack them in a jar then do the same, wouldnt even have to powder them.
Dosage would be hard to do but it's a clean method to avoid mush when filtering.

Indeed, it does work. Jees has done some work with the cold water approach. I was going to attempt his method but then life got in the way as it sometimes does! Here is the post:

CWE workflow on grinded syrian rue & no filter problems.

Yup it works. I do cwe extraction on my rue. I soak powdered rue in acidified water for a few days filter the liquid through an aeropress ( coffee filter ) then base and wash. Very easy.