I'm testing cvs integration using the checkin.php.
Using: SuSE 8.2/apache-1.3.27-99/mod_php4-4.3.1-178, the checkin.php was hanging forever. After some debug I've found out that commenting the line:
###########################################################################

INCLUDES

    ###########################################################################

    # Before doing anything else, start output buffering so we don't prevent
    #  headers from being sent if there's a blank line in an included file
    #ob_start( 'compress_handler' ); <- This one

It didn't hang anymore. (Don't ask me why, I no nothing about php4)
Firt problem solved (I guess)

Second, I've found out that $argv[1] was not returning the first argument. Actually, it was returning just nothing. So used "$_SERVER['argv'][1]" instead and it did ok.

None of this happend on a SuSE 9.0 box.
Using apache-1.3.28-77/mod_php4-4.3.3-189.
With this conf it work just perfect. I think it may the php4 version.