Normally Jira will automatically create all users it doesn't now (it will create them in the Interal Jira User Directory).
You could also migrate your users from Telelogic to your LDAP and then synchronize your User Directory in Jira, that might help.
Another way is to replace all references to your old Telelogic usernames with your new Jira usernames, if you have a list mapping the usernames you should be able to write (or find) a simple replace script to this in a single go.
Some more information about importing from a csv can be found here :
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