> Sorry, editing error: I meant to refer to Abulaziz's paper "Implicit
> phasing for R6RS libraries", available via ACM or Citeseer-X.

Please also check out Takashi Kato's paper "Implementing R7RS on R6RS
Scheme system" about Sagittarius Scheme at the 2014 Scheme Workshop
(http://www.schemeworkshop.org/2014/IndianaCSTR718.pdf#page=6). There's
some discussion of phasing and library interop.