Trying to install Horde

[linuxfast]

Firstly I am playing around on a test machine so doesn't matter if everything goes horribly wrong.

One of the options for the configure command for PHP that is required by the Horde framework is ``--with-dom``
I notice from phpinfo(); that ispconfig must have configured PHP with that option disabled.
If I use the same configure options as shown in phpinfo() only with dom enabled, do you see there being any problems ?
Which directory is the PHP source in ?

Any help appreciated

Edit: First problem is that apxs isn't installed, only for the ispconfig apache build which isn't apache2