[exim] Routing to another port on localhost: Trying to get P…

I'm making an attempt to get Exim to work with Puremessage.
Apparently you can set puremessage to act as an smtp proxy (just set
your 'port' and 'smtp_talk_port' directives in pmx.conf appropriately).

That done I want Exim to accept mail on port 25 but immediately send
it onto pmx which is listening on port 10025. Pmx then does its
thing and sends the mail back to Exim which is listening for it on
port 10026. Both Exim and puremessage are installed on the same server.

The first router in my exim.conf is :

--
pmx_smarthost:
debug_print = "R: pmx_smarthost for $local_part@$domain"
condition = ${if eq{$interface_port}{25}}
driver = manualroute
cannot_route_message = Unknown user
domains = +local_domains
route_list = * 127.0.0.1
transport = remote_pmx_smtp
no_verify
--

Any traffic that doesn't match it just falls through to the stock
dnsresolv, system_alias and localuser routers.

The remote_pmx_smtp transport is:

--
remote_pmx_smtp:
debug_print = "T: remote_pmx_smtp for $local_part@$domain"
driver = smtp
port = 10025
--

The problem I'm running into is that when I send a message to exim on
port 25 its not getting forwarded to pmx. Here's the log:
----
2007-08-30 15:52:23 SMTP connection from [206.190.37.196]:36228 I=
[128.100.xxx.36]:25 (TCP/IP connection count = 1)
2007-08-30 15:52:24 1IQq40-000B1O-2b <= fake@???
H=web88009.mail.re2.yahoo.com [206.190.37.196]:36228 I=[128.100.xxx.
36]:25 P=smtp S=1762 id=417421.81765.qm@???
from <fake@???> for fake@???
2007-08-30 15:52:24 cwd=/var/spool/exim 3 args: /usr/local/sbin/exim -
Mc 1IQq40-000B1O-2b
2007-08-30 15:52:24 1IQq40-000B1O-2b remote host address is the local
host: dollar.faker.utoronto.ca
2007-08-30 15:52:24 1IQq40-000B1O-2b == fake@???
R=pmx_smarthost defer (-1): remote host address is the local host
2007-08-30 15:52:24 1IQq40-000B1O-2b Frozen
2007-08-30 15:52:24 SMTP connection from web88009.mail.re2.yahoo.com
[206.190.37.196]:36228 I=[128.100.xxx.36]:25 closed by QUIT
---

Am I using the appropriate driver in the router and the transport to
do what I'm trying to do?