SR:IV's limit has been increased by far, or even removed. (homies.xtbl)In SR3 at least, there was a hard limit to the number of homies you could have, because the save file only had space for a certain number of them. Beyond that i assume you'd encounter save corruption or the extra homies would be ignored. I expect it's a similar situation for 4, if the engine would even accept a number beyond that in the xtbl file.
The DLC got around this by having a separate area in the save for DLC unlocks, and separate xtbl files.
You could try modifying the actual cell_phone.lua in interface.vpp_pc and see if you can remove the restrictions on the scrollbar.SR:IV's limit has been increased by far, or even removed. (homies.xtbl)
My problem is that I added several homies on top of the original ones, and now some of the original ones are disappearing in the Phonemenu.