From workflow you can obtain process creator, for example, using /process_data/@creator_id... is that the sort of thing you mean?
If your Livecycle server is synchronized with the LDAP database then you can use the LookupUser Component from Avoka
http://www.avoka.com to obtain the user's lastname, firstname etc.
Then use a setvalue DSC to assign these values into your form.
Cheers,
Lachlan
http://www.avoka.com