mibbit.com has a full function IRC client implemented in javascript and css, no flash, no java... It's actually not bad. It'd be a cinch to make a little iframe on the main page with a "click here to enter chat" button that links to an embedded mibbit window set to join laserchat.
alternatively there's jirc and pjirc, though iirc they use java and I really hate java.
Another option, other than laserchat's IRC is to set up your own IRC server specifically for LPF.. It's not all that hard to install ircd, and its default config is prolly just fine for a simple single channel setup like we have... I mean, there are ircd's coded for commodore 64's and the like, it's a protocol that's existed since the 1970's... I can't imagine it'd put much strain on the server. And actually, if you set up a really simple eggdrop bot running locally you could have it spit out HTML to a file that could be synched to a (within five seconds of)-realtime chat output directly on the main page, again, while putting a ridiculously low load on the server.