Okay, with everyone's help, I believe I have found a resolution to this issue. I am very grateful to everyone who has contributed this discussion. Your help has been invaluable.
1. The first thing I did was to ensure that the iCal and Wiki servers were both running.
2. Next, I created a user whose sole purpose was to create wikis on the server. (In retrospect, I probably didn't have to do this, as any administrative account, which is what I have, can also make wikis).
3. I then created a wiki. To do this open up your Web browser and enter in the name of your server followed by "/wiki" (no quotes). An example of this is servername.local/wiki. (If you are unsure as to whether or not DNS on your local network is working, you can enter the IP address of the server followed by /wiki).
4. Next login into the wiki by clicking on the lock icon in the toolbar. (You can use the account you created earlier or any admin account on the iCal server for login).
5. Click the Wikis button.
6. Click the plus sign in the toolbar, then click New Wiki.
7. Enter a name and optional description. It is much better to enter a short name with no spaces. This will matter in a later step.
8. Next you will see the Set Wiki Access dialog box. Here is where you can enter users of the wiki (calendar), and their permissions (i.e. Owner, Read-Write, etc.).
9. When done with the previous step, click create, and you should be taken to the "welcome" page of your wiki.
10. Click the gear icon in the toolbar then select settings.
11. Select Services in the sidebar, put a check into the Calendar box, and select Save.
12. You should now see a link for Calendar underneath your toolbar. Select it, then select Settings to adjust your timezone settings, etc.
13. You can log out of the wiki at this point.
14. Go to one of the users who was given access to the wiki in step 8.
15. Open iCal -- Preferences then select the Accounts tab.
**Now here is where things get "tricky."**
16. It is likely that this user has a functioning account on your iCal server. If you go to the Server Settings tab of the account and check the Server Path, you will see an entry similar to /principals/__uids__/longstringofalphanumericcaharacters/.
17. Replace the long string of alphanumeric characters with "wiki-wikiname" (no quotes). The wikiname is the name you entered in step 7.
18. Close the iCal preferences box, and close iCal.
19. The user may be prompted to re-enter his/her password. Do so, and afterward you should be have access to the wiki-based group calendar.
UH OH...what about the user's normal account?!?!?!
20. Go back into the account preferences tab of iCal and re-add the user's normal iCal account with his/her normal credentials. All of the user's calendar information should return because it is on the server and backed up regularly...right?
This solution appears to be working for me so far. I have verified that users who can only read from the wiki calendar do not have the ability to edit the calendar. Of course, those who can edit the calendar are able to do. These test users are also able to use their normal iCal accounts without any issues.