You can give any Eperson permissions to submit/deposit new Items into a Collection by doing the following (in DSpace 7):
* Login as an Admin
* Browse to the Collection & Click Edit on that Collection
* Click on the "Assign Roles" tab
* Under the "Submitters" section, click "Create". This will create a COLLECTION_*_SUBMIT group which gives anyone in that group permissions to submit to this Collection.
* Click on that Group name. Add EPeople to that Collection by searching for them by name and clicking "+" to add them.
Tim