Add following manually in shopping.dat file:
To section prices - section CarMods:
		bnt_a_ps		PSLBTA		respect 0 	sexy 0		600
		bnt_c_ps		PSLBTC		respect 0 	sexy 0		600
		fbmp_a_ps		PSLBMF		respect 0 	sexy 0		1000
		rbmp_a_ps		PSLBMR		respect 0 	sexy 0		1000
		misc_a_a_ps		PSLSLA		respect 0 	sexy 0		850
		misc_a_c_ps		PSLSLC		respect 0 	sexy 0		620
		misc_b_a_ps		PSLSST		respect 0 	sexy 0		400
		misc_c_a_ps		PSLSEAT		respect 0 	sexy 0		600
		spl_a_ps_b  		PSLSPA		respect 0 	sexy 0		900
		spl_c_ps_b  		PSLSPC		respect 0 	sexy 0		700
		rf_a_ps			PSLRFI		respect 0 	sexy 0		500

To section shops - section carmod1 (to make them appear in the mod shops):
		item bnt_a_ps
		item bnt_c_ps
		item fbmp_a_ps
		item rbmp_a_ps
		item misc_a_a_ps
		item misc_a_c_ps
		item misc_b_a_ps
		item misc_c_a_ps
		item rf_a_ps
		item spl_a_ps_b
		item spl_c_ps_b

Add following in gta.dat file:
IDE DATA\MAPS\veh_mods\postludeparts.ide

If you want to use the parts, replace string starting with blistac with this:
manana, bnt_a_ps, bnt_c_ps, fbmp_a_ps, misc_a_a_ps, misc_a_c_ps, misc_b_a_ps, misc_c_a_ps, nto_b_l, nto_b_s, nto_b_tw, rbmp_a_ps, rf_a_ps, spl_a_ps_b, spl_c_ps_b

If you want to use those as addon, change manana to pstlude or any desired name.