Found a good library to convert SVGs into Inkscape symbols.
There are a few of them, but SVG 2 Sprite is a simple and straightforward command line tool.
A sample command would be
svg2sprite path/to/source/folder/ path/to/destination/folder/sprite.svg
This one is a good read if you are into creating SVG sprites or symbol packs
Just in case you need more than a command line tool like SVG2Sprite, try this