Hi Glasgow123,
I have done something similar a couple times with different customers and followed this approach below. I am sure there are other methods but I had challenges with other attempts I tried...

?Categorize all contacts in sales reps current Outlook clients as “Sync with CRM” to flag these contacts to synchronize into CRM or give them Excel file template to fill in their contacts if they do not have them in Outlook.
?In Outlook Client - Export all contacts from current Outlook “My Contacts” to CSV file with default columns – Note that the category will be used to grab these contacts to bring into CRM
?Pull all these contact lists together into a master spreadsheet and utilize matching algorithms to identify duplicates and manually reviewing and removing records that can be deleted
?Extract all accounts from CRM into spreadsheet which will be used to match company for the contacts
?Import to CRM – Create contacts into CRM and assign to appropriate accounts identified. If no account associated then load the contact and do not set the account relationship.
?From this information, match the company names on the contact records with the accounts (fuzzy matching will be required)
?Contacts – Import cleansed contacts into CRM with appropriate owner on the account identified as well (this would be the sales rep). This means that the sales reps need to exist in CRM at the time we load this data.
?Note: Check duplicate matching rules in CRM and determine what you want to use:
?Contacts with same business phone number
?Contacts with the same e-mail address
?Contacts with the same first name and last name
?After importing these two entities the contacts will be downloaded to the “My Contacts” for the owning users after they have been setup successfully as a valid user in CRM and enabled.
?NOTE: This will mean that the users will have duplicate contacts for all the contacts that they sync’d to CRM.
?Backup their PST to a file – in case any issues…
?Verify all contacts that were synchronized look correct
?Select all contacts with category “Sync with CRM” and delete these contacts
Hope this make sense and helps!
Thanks much,