I don't have any advice to offer you on how to implement your method. other than suggesting that if you don't get enough useful responses in this forum you could ask in the API forum, where the macro gurus hang out.
I would question whether this is a good direction to go. Unless things have changed in the last year or two, I do not think it would be a good idea to try to work with 150 sheet drawings. I've never made a drawing with more than two sheets myself, but my understanding from following these forums is that SolidWorks starts to bog down when you get very many sheets, like 10 or 20, and I would expect 150 sheets to bring it completely to its knees.
Welcome to the forum.
I've got to agree with Jerry about that large drawing. I do multiple sheet drawings, usually not more than a dozen or so, but I have had a couple over 30 sheets. I wouldn't want to try one bigger than that. I would recommend having the BOM for your main assembly set to "Top Level Only" to point to your sub-assemblies, then detail each of your sub-assemblies in seperate drawings.
Getting back to your original question about linking sheet numbers in your BOM, I'm pretty sure there isn't a way to do it without a macro. As Jerry said, you might want to start a new post in the API section.
Thanks for the reply's chaps.
I have always been slightly dubious about multisheet drawings, but thought I'd bite the bullet and give it ago. Apart from loading and save times solid work seems to be handling the extra load well and so far I'm upto 87 drawings. As its just myself in design and development within our company I carry out everything from modeling, technical drawings to technical publications. So far I'm finding multisheet drawings are saving me an imense amount of time due to smaller, seemingly less essential factors.... however the time they actually save allows me to focus all my attention on design instead of formatting.
I'm suprised SW doesnt have a function to organise design drawings into a more indexed order.
Once I have my BOM sheet number macro set up this will reduce fomatting time further.
Again thanks for the advice, I will try in the API forum