Combine files on commit in Mercurial

Question

I've got a project with 2 files I want to source-control using Mercurial:

• A SCX-File which is a binary (database) file
• A SCT-File which is a text file

My filter:

[encode]
**.scx = tempfile: sccxml INFILE OUTFILE 0
[decode]
**.scx = tempfile: sccxml INFILE OUTFILE 1

Problem

• sccxml only receives the path to the SCX-File
• The SCX-File can not be converted to a text-file without the corresponding SCT-File

Workarounds

• Is it possible to combine the files before the filter runs?
• Is it possible to pass both file's paths to sccxml-Converter?

UPDATE:

No, I'm using not using the Win32Text extension. The SccXml-Executable needs both an SCT-File and an SCX-File as parameter to convert them to a Text-File (the text-representations of both files get tar'ed into one file).

I Want To have the binary files as Text-File in the Repo, to get meaningful diffs. I am currently trying to achieve this using a precommit hook.