I've determined the issue and will post the answer in case anyone else experiences the same issue. The problem was with the HTTP cache headers we were sending along with the font file. Apparently this causes IE8 over HTTPS to not load the fonts for some reason (if anyone knows the true reason please comment below). The successful headers should look like this:
HTTP/1.1 200 OK
Content-Type: application/vnd.ms-fontobject
Date: Wed, 26 Mar 2014 23:57:04 GMT
ETag: "08b27bc96115c2d24350f0d09e6a9433f"
Last-Modified: Wed, 26 Mar 2014 12:10:02 GMT
Server: Apache-Coyote/1.1
Content-Length: 38205
Connection: keep-alive
but instead were being sent like this:
HTTP/1.1 200 OK
**Cache-Control: max-age=31556926, must-revalidate
Content-Type: application/vnd.ms-fontobject
Date: Wed, 26 Mar 2014 23:58:06 GMT
ETag: "08b27bc96115c2d24350f0d09e6a9433f"
**Expires: Fri, 27 Mar 2015 05:46:52 GMT
Last-Modified: Wed, 26 Mar 2014 12:12:12 GMT
**Pragma: no-cache
Server: Apache-Coyote/1.1
**Set-Cookie: JSESSIONID=844B0798B373A3B8ED54A694C9DFB5C5; Path=/; Secure; HttpOnly
Content-Length: 38205
Connection: keep-alive