When I got my first P30, I hand on hand my first IPSC speed holster for HK USP: Hoppner and Schumann Speedsec 5CW. I modified it to work with P30 using Dremel tool with cylinder shaped milling bit and hand file. 5CW is made from polymer so use low speed and work slowly to not overdo. Modified holster still accepts HK USP, but also works with USP Compact, P2000, P2000SK, P30, P30L, HK45, HK45C and even HK P7.
To make P30 fit into holster, I used Dremel High Speed Cutter (115). With this bit I made opening in holster wider in back part (see picture). Wider channel reaches as deep as to locking claw and this claw is also partially undercut to allow engagement on triggerguard to lock out holster. This allow wide portion of triggerguard to slide into created channels. This also generate very positive gun retention in holster, while only short up movement is needed to allow moving gun forward. Wide portion of triggerguard does not need to fully clear holster opening.
I hope this short guide and pictures will help to do this mod (please take note, that holster on photos is left handed version.. I'm not aware of dedicated HK P30 IPSC speed holster, so this may be good solution for P30 owners shooting IPSC. For those looking for classic style IPSC holster for P30, have a look at Comp-Tac International holster with drop offset mount.