Currently the ContextSelectors in Logback are limited to Default and JNDI, whereas a system property leads to ContextJNDISelector being pulled.
This stuff is all hardcoded therefore not configurable.

I cannot use ContextJNDISelector because of a bug in Websphere 6.1. In WS 6.1. env-entry values are seemingly bound to the JNDI at a very late point.
This leads to that the JNDI lookups fail because Logback initializes (through jlc-over-sl4j) way earlier in the application startup phase.
It boils down to that I cannot use ContextJNDISelector in WS 6.1.

For this reason I wanted to provide a custom ContextSelector to Logback, which is currently not possible.