Jack -- you're safe as long as you never click on "deposit week" or put your credit card in to make an exchange.
-- Enter Search parameters (I usually check "all" and search for about a 13-month period)
-- Click on the unit you want to search with (your Starwood unit)
-- Depending on how your week was set up (e.g., fixed, float, lockoff), you may be taken to a screen to select a week to search with and/or a unit size -- this allows you to play with different weeks and unit sizes to find the most powerful weeks
-- Once you submit, the available locations will appear
-- Click on Aruba (for example) to see all available resorts/weeks/unit sizes in Aruba
If you eventually find something you want, you can make an "instant exchange" by clicking on EXCHANGE and submitting your credit card info. But, then Starwood has to confirm the week you selected (which gets tricky, since they like to control the deposits and assign something that they already deposited as part of their bulk-banking process). They will probably try to give you something else, and at this point you need to get a 3-way call going with II and Starwood to make sure II can switch the trade to the new deposit (it has to have at least the same amount of trading power).
Here's an example:
Say you're searching with a "mythical" week 11 2-BR in Orlando. Week 11 is pretty powerful even in Orlando, so you'd probably qualify for a 2-BR Maui/Kauai/WSJ/Harborside week if one were available. You grab it. You call Starwood and they decide to give you week 37 instead of week 11. Chances are, week 37 in Orlando won't qualify you for a 2-BR in Maui/Kauai/WSJ/Harborside. You can't risk losing your trade by allowing Starwood to just start switching things around. You need to get II on the phone -- they can "hold" the unit for you until Starwood assigns you something with enough trading power to qualify for the same trade. I generally search with weeks for which I have a confirmed (but undeposited) reservation. The fact that I have booked a particular week has helped get the same week deposited (but, it's still not easy!).