@laurentc
I just downloaded 0.9.7-alpha-1 and installed it in MAMP and so far I LOVE IT! However, I seem to be having the same problems you are with getting core snippets installed in the alpha version.
The only documentation that I could find for installing these core snippets was ---->
http://svn.modxcms.com/docs/display/MODx097/Package+Management.
According to this page, "Package uninstallation is shaky at best in 0.9.7-alpha; some files may or may not be removed. Use at your own risk, as you might have to go manually delete files if not removed.
Also, packages cannot at the moment be updated remotely. Trust us; we’re working at full-speed to make sure all the features are seamless for beta and onward." which is very understandable being that 0.9.7 is an Alpha build.
However, I followed the instructions listed on that page and tried putting the Wayfinder 1.0.1 Beta Zip File in my core/packages/ directory, and then running the Workspaces section of the manager. From there, I clicked on "Add New Package", and selected the "Search Locally for Packages" option. MODx should have then scanned the core package directory, and added any packages I put there. Sadly, it didn’t work. Then I tried unzipping the Wayfinder zip file into it’s own folder located at core/packages/ and tried installing it again through the manager. Again, no luck.
Are we missing something here? Should this be working?