First off, the software you need is Sound Bridge, not Soundiver. You should be able to download it from Alesis'site. If not let me know - I can probably email it to you.
Assuming that you have the DM Pro hooked up to the computer, when youopen up Sound bridge, under the Project menu, you need to set up your MIDI ins and outs. You can also test your MIDI setup to make sure the software sees your DM Pro. Also under Project, set up the card info so the software knows it has 8MB.
Now, you are ready to add samples. On the left, there are 8groups. You can add your samples to one big group, or divvy them up (I made separate groups for snares, kicks, etc). Highlight the groiup you want to add your samples to, then click the Add Files icon (2nd icon from left). browse for the files you want to add. Once you find them and click on them, click Add (you can add multiple files by the usual way).
Down towards the bottom center of the screen, the software will tell you how much more room you have on the card. When you are done, click the Send To Synthesizer icon (last icon on right). It takes awhile, so get a cup of coffee or beverage of choice at this point
Once the card is burnt, you will need to go into the DM Pro and create User drums from the samples you have made. Somne folks have forgotten this step (myself included) and get panicky that it didn't work. Somefolks will do a reboot of the DM Pro while holding both sides of the cursor button down - this boots up the DM Pro with no kits, drums or effects loaded. Then they will go into the USer drums and create their drums from the samples. This way there is no carry-over from effects or other settings to distort your sample sounds. Again, you can refer to the manual, or email me, and I can send you more info (!LOL).
Sorry to be long-winded, it comes naturally, as creating documentation is what I do for a living