Splits training. Warm up with 30s in each split, then do 60 in each split, then do 90 in each split at the end of your workouts.
Pullovers. Simply need to do pullups and leg lifts.
Pullup with body horizontal ( parallel to ground ) or jumping pullup, hold top for 5 and lower for 5 or pullup and lower for 5. If you can do more then you start doing pullups in tuck or L or wide arms.
Leg lifts. Start with lying on back lifting legs up off the floor to over your head. Then work hang from bar and lift legs to tuck. Hang from bar, lift legs to L, Hang from bar, lift legs to bar. Hang from bar, lift legs to bar and hold for 3,5,10seconds. Hang from L, lift to bar, hold and lower down.
FHS requires a decent HS and an aggressive kick from a lunge. Practice lots of free HS and wall HS or wall HS shrugs/pushups for strength. Practice Bridge wall walks ( take one big step from the wall then bend backwards and walk down the wall to bridge and back up ) and Front limber ( handstand to bridge and stand up ).
Doing 5 sets of wall HS should cover it. Think 20-30 lunge kick to HS, possibly 50. This is either sets of 5 or 10 kick to HS.
BHS needs a good HS and it's a good idea to be able to do some sort of bridge kickover/walkover/backebend, covered above and the leg lift strength besides leg strength. For leg strength, lots of squats and lunges. 5 sets should be good. To be simple, go for nearly as many reps as you can. You can get into more complicated rep schemes later. This will work for you.
Do a set of pullups and then a set of HS stuff and rest for 2m. Repeat 5 sets.
Do a set of leg lifts and pair it up with lunges and squats. Rest for 2m. 3-5 minutes is better, but it depends on how time you have. These long periods are so your body's energy system can replenish and this is focused strength work not conditioning.