My suggestion would be to read through the material at
https://wiki.debian.org/DebianMaintainer and take it from there. Sounds
like you're about where I was when I started with Debian in 2003: I was
experienced Linux/C/C++ developer using tiff, xerces, and icu at work. I
took over the packages with the help of sponsors and initially as a
co-maintainer and used my experience there toward becoming a full debian
developer about 18 months later.
I'm afraid I don't have time or energy to help with the sponsorship, but
maybe you can find someone who can take over maintaining icu with the
intention of sponsoring you or who can sponsor you to take over
maintenance. I got my start with the tiff packages by managing a
transition that corrected an inadvertent binary compatibility problem
without an soname bump, and through that, earned enough of a reputation
to be able to move through the new maintainer process pretty easily. ICU
presents an opportunity to do something similar. Take a look at
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=757025. When I created
that, ICU 53 was out, but I was not able to get the transition done for
jessie. Now ICU 54 is out, and one of the first jobs of icu's next
maintainer will be, post jessie, to orchestrate a transition of icu to
version 54.1 or whatever is current at the time. This would be a good
way to cut your teeth on slightly more advanced package maintenance
activities required with library packages.
--
Jay Berkenbilt <qjb@debian.org>