cck integer field - value and text representation

Hi

I have a custom content type and it's first two fields are month (field_month) and year (field_year). The month is a cck integer type field and it's value list is

1|January
2|February
3|March

and so on.

Using pathauto I'd like the url to be in the form mysite.com/newsletter/2007/5, but what is happening is I'm getting mysite.com/newsletter/2007/may.

The only token available to me is [field_issue].

Any idea how I can have it use the key value (eg 5) instead of the label (eg may)?

thanks