I believe not. You can import a contacts list if exported from Outlook own .CSV format, but I do not believe you can import a distribution list.
To import contacts from which to build a distribution list in webmail,open webmail, choose Preferences from the top bar, then Address Book, then the Manage Address Books page, where there is an option to import address books.
You can also set up Outlook to access your Telus email account as described in your other post, which I expect would be a lot more satisfactory for your needs.
PS. It might be worthwhile to start researching a replacement for Outlook 2007, as it will likely be orphaned by Microsoft in the next year or so.