I was having a look at the module and was kind of hesitant to try it further after seeing it required to modify a core file.
It is only a slight change and would be easy to include it as a patch to be run when updating, but in the spirit of all good things Drupal, I was wondering if there wasn't a solution to avoid that patch all together.
It seems that what you're asking to add to common.inc is to have the url rewritten to handle sessions on Docomo cellphones.
Might I suggest to have a look at this nice little module and see if this would let you achieve the result you seeked:
There also a core drupal function to rewrite the inbound and outbound urls, but it requires you to write the rules in setting.php which is a bit ackward (that's why url_alter was written to solve and those hooks are now part of D7 core). Here's a reference to it: http://api.drupal.org/api/function/custom_url_rewrite/5
Please let me know what you think and thank you for this module.