Once in the live cd /dvd or installed version run in terminal / konsole as root:
See if the wifi card is listed as unkown or rev2 something something.
If this is showing usefull info tere for the wifi card then right click knetworkmanager top right next to time and select wifi network or as root in terminal /konsole
then follow the questions , if you only see say b44 or lan and no wifi type anything then stop.
99% of the wifi / networking stuff works the same in gentoo / SL with exception to names / drivers.
You can try the sticky top of networking about "before 3.4e ipw3945 ...." and use it as guide + adding the windows driver you have for the wifi card you have.
Recommended to try the win xp pro 32 or 64 bit drvers if available with ndiswrapper.
remeber the stuff posted there like 5 times modprobe -r and stuff is there for a correct reasons and would need to be followed up until you have wifi connection as this can happen like it is there.viewtopic.php?f=52&t=8933
I did post a ibiblio.org link to my bcm4311mcg Dell wifi card for win 32bit and likely it should work for you card as well or using the ones you have but might need to extract you hp drivers and or search for them.
Unloading modules think it is bcm43xx then ieee80211softmac , ieee80211 , ieee80211_crypt then modprobe ndswrapper .
Hope this helps or follow the links at the bottom to gentoo netwroking guide or try our wiki top right of this page + wifi guide there one of them would work for you.