From Hostgator Tech (see my email to them below):

Unfortunately because of the requirements of the elgg software we are
unable to accomodate your request on a shared server.  If you would like
to purchase a dedicated server, then this could be done.

With this software, PHP 5.2+ needs to be installed as an apache module
(not in CGI mode or safe mode and we use suphp mode, which uses CGI)

http://docs.elgg.org/wiki/Installation/Requirements

Angela
Supervisor
HostGator.com LLC

> I need some kind of response to this inquiry. Having researched other open
> source social networking apps, I am convinced that for my purpose, elgg is
> easily the right choice. Therefore, I either need hostgator to agree that
> I can install it or I need to find another host. Could someone please
> respond? Thank you.
>
> Jack

>

>>
>> I was told this was the email address to use to convey my
>> displeasure at learning that your hosting company will not
>> support my elgg install. <snip>  elgg is an open source
>> social networking CMS that is on your incompatibility list.
>> Why is this? What's the problem with it? I installed and
>> have been trying it out for several days already
>> (http://stained.me/elgg/pg/dashboard/) and it's worked
>> fine so far. What gives?
>>
>> I don't understand why I can't use this software and would
>> like an explanation. I am paying you a hosting fee and was
>> not aware of this limitation when I signed up. This is very
>> disappointing. I recently rated your hosting service very
>> high and recommended it to friends and colleagues. I now
>> have to rethink whether or not my site would be better
>> served by another, more hospitable host provider. An
>> explanation, however, would go a long way to placating my
>> concerns.
>>
>> Thank you.
>>
>> Jack