The package is called tslp by Exar. Below is what I hope is an appropriate footprint (as Exar only has the package footprint not a recommended pcb layout, not does anyone else I can find). I took the ITG-3200 (which I assume is what you used as the base of your part) qfn-24 4mm footprint and reduced it to .4mm pitch .24mm pad width (pin is .2mm nominal +- .05) and .6mm long. extending .2mm outside the 3.5mm package boundary (because that is what the 4mm part does more or less). You should be able to replace your parts current pcb svg file with the one below (it is really a .svg renamed to .fzpz so the forum will upload it, it doesn't always like svg files) and copy it over your current pcb svg file either from the command line or via parts editor. You likely want to print a copy of the footprint and check it against one of your ICs to make sure I got it correct though 
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svg.pcb.qfn24_3_5d0adadc93770fb556e0d9444d0035ec_1_pcb.fzpz (9.2 KB)
edit: not quite right yet. Fails drc on overlap and some connections look wrong. I'll have a look and upload a corrected version. May have to reduce the pad width to get by drc. Turns out to be mostly a false alarm. The original part doesn't use all the pins, thus they aren't all active and the original foot print also fails drc so I guess we live with that. I did however update the above file as I reduced the pad width from .24 mm to .22mm to increase the inter pad distance by a whole .02mm (but every little bit helps ). the pin is .2mm nominal +- .05 so there is .01mm either side of copper. In addition I noticed that the center pad is a heat sink and is 2.2 mm square. The current pad was only 1mm square, so I increased it to 2.2mm. Post if you have questions. Feel free to upload your sketch and we will check it over for you. Please tell us if the footprint works, if so we can add it to the library.
Peter