Personally, I don't have alot of time. I understand, however, that time should be made for weight training for boxers, as when two equally skilled fighters square off, the stronger of the two will often win. My training regime has no room for 3-5 days of exclusively isolation exercises, as in order to be a better boxer, one must box. If I was training you and you were spending more time in the weight room then boxing, well, I wouldn't be training you for long. Compound exercises are my solution.

I include 2 days of weights in my training, on Wednesday and Saturday, both days when my boxing gym are closed. Bodyweight exercises, plyometrics and compound lifts are all present in my routine. Some of my favorite and common exercises are:

Squat and Press
Power Cleans
Bench Press
Dumbbell Snatches/Swings
Pull-ups (all variations)
Push-ups (all variations)
Clean and Press
Squats

Some effective plyometrics:

Neider Press
Clap push-ups
Medicine ball throws (overhand, backwards, cross, jab, etc)
Squat jumps
Lateral jumps
DB axe swing

These exercises are all great for a boxer's training schedual, and I highly recommend any and all of the above. Compound exercises combined with plyometrics can increase lean muscle mass, which is REALLY important for me to stay within the confines of my division while gaining explosive power. Good luck and train hard.