Does anyone have any experience using perl or any other regular expression parsers to convert an /etc/passwd file into a format compatible for use with lat-users so I can batch import?
I am not sure if the /etc/passwd file contains enough information, have a look at the examples in /usr/doc/lazy-admin-tools/ it seems that you need at least the login name, firstname and lastname, the first is in there, the latter two could be in there but it is one field, so you would need to define what you want to do with that field, split it where possible, or do not split at all and add it to either firstname or lastname field.
This is just from looking at the docs as I have never used the toolkit.