I just uploaded an antlr grammar I originally wrote for pyparsing and
that I could convert to lepl... Since I couldn't find any way to
upload a file here, I opened an issue (it is marked as defect, but it
really an enhancement I mean...) and explained there some use case :

http://code.google.com/p/lepl/issues/detail?id=19

The grammar is not complete, but it is working in many cases (one
example grammar taken from the antlr tutorials is part of the tests).
It works like this : it can parse an antlr grammar (
http://www.antlr.org/grammar/ANTLR/ANTLRv3.g ) using lepl rules, then
it uses the parsed rules to create equivalent lepl rules.

Included are some tests, it still lacks single lines and multi line
comments, and also rewrite rules (I think that they should be mapped
using Apply() in lepl, but I am not completely sure).

If anyone finds it useful and needs some extension, I will be glad to
work on it :-)