I have a few servers with gentoo linux. I know you don't support it, but maybe you could do advances install?
Even not in the form of script, but one of 2 options:
1. Possibility to configure something like "manual distribution" - so set all needed paths/binaries/libraries by hand. Instead of trying to detect them only on few distributions you're supporting
2. More documentation what stackify agent is doing after detecting distribution - then maybe I could set up my Gentoo to pretend to be one of supported distributions so agent would start working.
Both of the ideas could be not supported, only for experienced users.