Yes, it is possible to brew with acacia powder, but where you get that is your own business

Fortunately, (live) Syrian rue seeds are widely available as incense at middle-eastern grocers.
All of our rules of engagement are laid out here:
wiki.dmt-nexus.me
The basics of ayahuasca can be found in the
ayahuasca subforum under the section
preparations and methods of administration - but you are, to a large degree, correct in saying that the overall principle consists of combining a β-carboline plant with a DMT plant.
Not all β-carbolines are equal, however: harmaline is more 'intoxicating' than harmine, while some of them, like harman, seem to exert an anti-psychedelic effect - as I found out while experimenting with sea buckthorn. In a similar vein, caapi is particularly valued for its THH (tetrahydroharmine) content. THH has practically no MAOI action but is instead a SRI (serotonin reuptake inhibitor).
The 'golden triumvirate' of harmala alkaloids has its own set of beneficial effects, independent of tryptamines like DMT. Indeed, powerful visionary effects have been reported from harmalas-only brews on occasion.
People have experimented with Desmanthus plants, and D. leptolobus is said to be more consistent than D. illinoensis. They both seem to require several years to become established before producing usable quantities of alkaloids, and illinoensis has a tendency to produce significant amounts of the less visionary NMT. How that might affect one's experience is something of a matter of personal taste, but it will generally make a DMT experience milder and more 'somatic'.
We have a whole lot of information on which acacias are active - both consistently or inconsistently. It's an ongoing work-in-progress. Get your acacias started now! (Or at least when seasonal conditions permit.)
Here are a few pointers to get you started:
This is an acacia no doubt on the radar of many psychonauts hoping to grow their own source of tryptamines. Its a fast growing, frost and drought tolerant, foliage/floral abundant species; which can contain good levels of tryptamines in its phyllodes.. rendering it an especially appealing...
forum.dmt-nexus.me
..INDEX OF THIS THREAD [yellow links to relevant post] note: the main objectives of this thread, when it started in June 2011, were: 1) to improve the veracity of phytochemical info on Acacias worldwide 2) to encourage SUSTAINABLE use of Acacias, by growing 3) to find enough active species...
forum.dmt-nexus.me
For much more Acacia info (geographical areas and identification, sustainable harvest, alkaloid content, etc) Read the Acacia Info Thread Results are discussed throughout thread with more details. Ratios and percentages are approximate and subject to revision :) Acacia dealbata rootbark...
forum.dmt-nexus.me
Propagation of Acacias This thread is a dedicated space in which nexians are welcome to post their progress/knowledge in propagating acacia. Share techniques, grow logs, media, failures/successes, seed sourcing/collecting and any other propagation related info here. I'd love to see what members...
forum.dmt-nexus.me
..here is a recommended list of the TOP 8 ACACIAS TO GROW orientated for Nexians.. all except confusa & simplex [Pacific Ocean] are originally australian native, therefore will in most cases tolerate temperatures down to minus10°C (to minus12°C in one German report) A. floribunda is already...
forum.dmt-nexus.me
Besides that, have a scroll through the whole
forum and acquaint yourself with the
search function to see if you can coax it into generating a meaningful output
One more thing to consider - particularly if you're still waiting for your DMT plants to grow - is 'psilohuasca'. This is the possibly self-explanatory combination of a harmala source with psilocybin mushrooms.
Go easy on the mushrooms! They are greatly potentiated by the β-carbolines, sometimes to a startling degree.