Editing XPath expressions (Was: Replacing = with == an

... which brings up a point I've wondered about for quite a while.
XSLT allows me to transform XML, obviously including XSLT.
XPath is a big part of modifying/mutating XSLT because it allows me to
relatively easily address structures/constructs within my XSLT
program.
But when it comes down to it, I'd also like an XPath-like-language
that implicitly lets me parse/address XPath within XSLT attributes
(like select=) in order to gain further insight into what a particular
template/routine/etc is doing (and whether I need to modify it via my
XSLT-transforming-XSLT program.

The immediate context here is that I wanted to respond to this poster
saying: "Just invent your own derivative of XSLT where you have your
own token preference..." and that would work except for some nastiness
which would come in when parsing the actual XPath expressions to
differentiate between something like: select="*[@foo='bar']" and:
select="'my string with equals = in it'" (or in this case, the wonky
derivative with '==' instead of '=', though I don't pretend to have a
valid case for it).

Anyways, I've had this problem before, where I wanted to modify
existing XSLT programs in a particular way, but would need to have
insight into the XPath expression that would be a whole lot of parsing
work.  Previously, I've resorted to dangerous hacks with regex or
tokenizing, but having some sort of xpathpath would be better... even
if it didn't include xpathpathpath and further recursions.