As far as I'm aware, there aren't any rules that would allow you to use spell points to add charges to any magical item. You could potentially use rituals in order to recharge them. That would be somewhat funky on the bit that requires the spell caster to forgo a prepared spell or spell slot in order to recharge the stuff, so it would need DM approval. Though anything you do at this point is pretty much house-ruling it anyway.
Just giving up one spell point doesn't seem equivalent to losing one spell, especially not for high-level spells. Caster level should probably be a requirement as well (something like CL equal to staff's CL, or the level at which a Vancian caster would be able to cast the staff's highest level), and you should probably need more spell points for high-level spells. You could consider something like 1 SP for spells up to 3rd level, 2 SP for spells between 4th and 6th level, and 3 SP for spells between 7th and 9th level. This seems to fit reasonably well with the SP cost for using advanced talents (which mimic high-level spells).
There's actually something in one of the spheres that explains how many spell points equate to a spell slot, it's 1 spell point for levels 1-2, 2 for levels 3-5, 3 for levels 6-8, and 4 for level 8. I'd agree that it would most likely need DM approval but those are the numbers that I found.
It's specifically under the Mana Bleed Talent that I found the numbers. Creatures that possess spell slots instead lose spell slots, based on the level of the slot. Each slot is equivalent to a number of spell points: level 1-2: 1 spell point, 3-5: 2 spell points, 6-8: 3 spell points, 9: 4 spell points. The target creature chooses which spell slots are lost.