Wine's site (winehq.hu) has instructions on how to install Wine on some specific distributions. Three are also instructions for Fedora Core. The same instructions should work for RHEL too (as RHEL and Fedora are very much of the same base). Or you can just download the Wine rpm from Wine site or rpm.pbone.net and install it by double-clicking on it, or by commanding (as root)
rpm -i wine-versionnumbers.rpm
where versionnumbers depends on the package version. Or if RHEL uses yum like Fedora does, you can probably just
as root and have it installed. Then just run the IE setup with wine from console;
as a regular user; Wine doesn't seem to work well as root. Of course you must issue that command from the directory where setup.exe (or the file you want to run) sits.
I know a lot of companies, part of which are "Microsoft Gold Partners" or something, and use programs that work with IE only. That "Gold" partnership with Microsoft especially means Microsoft gives the company a "good boy, your software is valid for Microsoft products" stamp, if they create their products in such a way that they work flawlessly with MS products (and not so well with anything else, usually). The base line is that still, with a lot better and more standardized products (like browsers) around, there are a lot of folks that still develop programs (and websites and website programs) that only run on IE. It's sad, it's stupid, it's everything but future-oriented developing, but so it is. With Wine we can luckily get past this, at least in some cases.
One thing they didn't think about is that some programs that have been written to work with IE6 (and perhaps 5 or even older) surprisingly don't work with IE7, which is used by Vista and XP SP2. I know already some MS "Gold" partner companies that MS has said their products are 100% IE-compatible, but all of the sudden an upgrade to IE7 broke the programs: they don't work with the new version of Internet Explorer (and it's not because IE7 follows strictly standards; it's still an a-hole, but seems it's backwards compatibility is now also broken).