Yep :)
There is two ways i use.

Download Matt Zagoren performance data from avsim libruary. Search for 707perf.zip

First one can be used for fuel planning for 5-6 hour trips, or shorter. I use it almost every time. Its not precise but it does its job.
longer routes require wind corrections.

1. You estimate your cargo and pax load. assume that 1 passenger weight around 175 lbs.

2. estimate cruise fuel by fuel flow.
(Flight level   - Fuel Flow)

FL 360 FF 3300
FL 350 FF 3500
FL 330 FF 3900
FL 310 FF 4200

Using route length calculate cruise time for groundspeed 470 KTS. You can add wind corrections here, but i didnt found reliable wind data source. I fly in VATSIM almost all the time, so i use vatsim weather, - it may differ a bit from what FSX using as default.
Dont take into account climb time - just take entire route length and divide it to speed. -you'll get time, and multiply FF by that time by 4 engines.

Now you have your AC weight + pax + cargo + cruise fuel weight.

Estimate your takeoff weight by using TO and CLIMB table from Matts data. Estimate TO fuel by table and see if you guessed right, coz there are many tables for different TOGW there.

Add extra fuel for divert and so on, BUT NOT LESS than 10 000 lbs. Dont want to divert\hold, still add 10 000 lbs anyway.

See if you selected suitable flight level (tables will show it), if not - recalculate cruise fuel for lower\higher FL and repeat all steps after that.

Climb as you should, and after reaching your cruise flight level set engine cruise power by using Fuel Flow meters. That'll give you M=0.82 - 0.84 crz speed.

After stabilizing the speed in cruise flight - check how much fuel you burned. It should be close to numbers, CS 707 burn right amount of fuel in climbs.

Use Doppler nav system to get Ground Speed, or use chronometer to measure your average segment speed. (i do that in 727, in 707 i use DNS)
By knowing your speed, every radio fix or waypoint - you calculate how much time left to destination, and how much fuel will you need to reach it. Skip descend in your calculations. By knowing that - estimate how much fuel you will have on arrival.
See if you too heavy for landing, if wind around +-50 kts - you'll be fine

IF you have strong tailwind, like 100 kts - you'll be too heavy to land. Do not take any measures until 1 hour to TOD. Estimate landing weight around 1 hour to Top Of Descend point, and request lower flight level - burn excessive fuel by flying low.

That'll do the trick.  By doing that - i always arrive close to Max landing weight. Very rarely i need to burn fuel by cruising low.


Another way - to use figures from Matt's data, but you'll require reliable wind data. i dont have it. so i dont use it.

If you fly in vatsim you can get wind data by looking at aircraft's speeds along your planned route. Use VatSpy for that. Say you'll fly to the east. You see one 737 flies west at 500kts, one 737 flies east at 400 kts. Assume that steady air speed of 737 will be 450 kts. - you'll have around 50 kts headwind.

Ask questions - i fly 707 regularly.