Thanks to all the people who posted this. I just installed Fedora Core 3 on a HP ProLiant ML110 with a Digium TE405P and it's working great thanks to all the info I gathered from here. I compiled everything like it says here, installed the service, modified it with a pause between modprobe zaptel and modprobe wtc4xxp, and another between that and ztcfg, and now it boots to asterisk being ready to receive calls with an IVR I setup.
BTW this is deployed inside a cellphone company in the Dominican Republic. So the calls come from cellphones, through two T1's (that was also very interesting because ISDN is not supported here and SS7 is not suported by asterisk - the middle ground was D4, AMI and supposedly E&M wink on their side but I had to set it up as featdmf on asterisk, and the caller ID comes in as the called extension...)