My company spends a lot of money with Overture so we are what is considered a Platinum account. Even with this status and our own account rep, I still had problems submitting about 19,000 terms last week.
Regardless of your account status, all your terms need to be sent through their editorial approval process which checks for unique links and "acceptable" content in your description. They also check the number of impressions delivered for that term to see if it's viable.
Here's a quick guide based on my last submission.
AccountID - Obviously your account number. Must be copied to each row in which you have a term.
Search Term - You terms, one per row.
URL - target URL including tracking strings.
Title - the header displayed for your ad.
Description - text under ad.
Advanced Match Status - Might want to set this to "off" initially. You can find out more before you turn it on.
Standard bid - Your max bid
Content Match - See Advanced Match.
Content Match Bid - See Standard Bid.
Excluded Words - If you sell widgets but not yellow widgets, exclude yellow.
Category - You must create a category in your account first and then place that category name in the appropriate row for each term. I usually create a separate template for each category.
General advice - I usually send in batches of under 5,000 keywords. If you have an error in your spreadsheet, you will know immediately. Submissions take 3-5 days to be approved.
Good luck. Let me know if you need more assistance. Due to time constraints, I'm not on this board as oftern as I would like, so feel free to email me.