IIRC, several Republicans in Congress were pushing the legislation for several years before it finally passed. It passed with a veto-proof majority, so Clinton (effectively) didn't have much choice but to sign it.
<goooooogle...>
The [link|http://www.fas.org/news/iraq/1998/10/981009-in.htm|vote] was 360 to 38 in the House, unanimous (by voice) in the Senate. Even if Clinton had wanted to veto it, it would have become law on override.
Cheers,
Scott.