Weightlifting program is as follows:
1.) Lat pull downs(upper back; pull phase of stroke)
2.) Leg extensions(upper legs/quads; supports weight-catching phase of running and builds additional muscle massnecesssary for half marathon distances and up)
3.) Leg curls(upper leg/hamstring; boosts pull through for both cycling and running)
4.) Bench press(chest; improves pull phase in swim)
5.) Squats(glutes and quads; generates power for cycling and strenght necessary for hilly running)
6.) Lateral dumb bell raise(shoulder joint; supports healthy shoulders to prevent swim injuries)
7.) Calf raises(lower legs/calves; helps push-off for running)
8.) Dumb bell pullover(works all muscles in catch phase of freestyle stroke)
9.) Backward lunges(adductors and glutes; targets all muscles in push phase of hilly running)
10.) Biceps curl(front of upper arm; assists in part of the pull phase in the swim and provides climbing leverage on the bike)
11.) Triceps extension(back of upper arms; maintains form through back half of swim stroke)
12.) Leg press(glutes and quads; most important exercise for developing power on the bike)
There are 4 phases, adaptation, endurance, power, and chisel.
Frequency is 2 sessions per week seperated by at least 48 hours.
Adaptation - 1 set of 12-15 reps of each exercise mentioned above. Should not feel any major muscle burning at the end of the set. When no soreness occurs the next day, move onto the next phase. This phase will last 2- 4 weeks.
Endurance - same as adaptation, this phase consists of 2 sets of each 12-15 reps and will last 8-12 weeks.
Power - 1x10, 1x8, 1x6, are the reps for this phase, give it your all, the last rep should be max effort, do thses sets twice a week, this pahse lasts 4-6 weeks.
Chisel - this set is similar to endurance, except with a slightly lower weight, the key here is to apply speed while maintaining form, this is also where you will become most fatigued(from speed, not weight of sets). This phase should last 4-6 weeks or end at least 4-6 weeks before your event.
Remember that form is paramount slow and controlled motions are recomended for all lifting with the exception of the chisel phase, hopefully you will have gained good form by then.
Good luck, train safe!