If your bellows is taped black youll only need to do the worn lengths. Youll be able to get short roll tape & plenty adhesive from CGM for a c£12 + postage.
http://www.cgmmusical.co.uk/CGM_Musical_Services/Bellows_Tape.html
Youll need to call him to get the nearest pattern match for yours.
The bellows will part & go back together with no trouble in my experience. And your hands can get messy with white glue, so you dont want to be having to handle any other parts of your instrument.
If not obvious mark the bellows front on the wood with a penciled arrow so you put it back the right way for sure.
Keep the pins in order (stick them in a bit of masking tape mark no 1 so you know which way round it is) & put them back in the same holes when you replace them.
Cut the tape square & accurately.
I warn you it can be a bit frustrating as it doesnt want to stick at first, see 2nd vid below, but it does in a few mins. Have a couple of damp (not wet) cloths ready for your hands (as sticky fingers will lift it off again) and for excess adhesive that is squeezed out as you apply the tape... make sure the edges accurately line up with above & below both sides.. and that the tape folds are equal either side of the bellows fold... or it will look amateur. Do one strip and see how you it goes. If happy & confident do the rest that need doing.
Dont remove the bottom one (or top, but you wont usually need to do that) its put on before the wood, so its tucked in and glued. If you feel you have to do the bottom, come back for more advice.
Make sure excess adhesive is wiped off everywhere with your damp cloth as you dont want to stick the bellow folds together.
If not confident, put grease-proof paper slips between retaped folds to be on the safe side - you could stick to the grease proof paper which aint great - but it aint ruining the bellows and the greaseproof will rub off with your damp rag.
Rinse the cloth out regularly so youre not handling a gluey cloth.
Do all necessary replacements on one side, and then compress the bellows with a weight to keep tape in place and leave for a couple of hours or so to dry, before doing another side.
Leave overnight and reassemble the bellows to the KB & bass. Take your time dont panic and youll be good.